support for QB 2016 for Mac Desktop

Try searching from here: https://quickbooks.intuit.com/find-an-accountant/

Enter your city or zip code then specify the supported product in the search criteria. 

It is not common for QuickBooks to delete transactions.  And it is almost impossible for it to delete entire years worth of transactions.  Has QuickBooks been making backups of your file when you quit?  If so those should contain all the transactions up to the point of the backup. Restoring those may be the solution.

It may also be damaged indexes in the data base. First try File->Utilities->Rebuild and see if that brings them back. 

If that doesn't work... the other most common way transactions are lost is when someone opens an older copy of their company file.  The transactions just aren't in the older copy.  You may want to see if you have other copies of the company file - particularly if the copies are larger on disk.  You can search for them with Spotlight in macOS. Look for .qb2016 to find all the company files on your disk. 

@Danuta 

I am agreed with @IntuitBrooks . You may have more than one company file on your Mac.

Thank you for responding to my question. What I didn’t mention in my original post were the circumstances that led to the data loss. Last month I attempted to upgrade from High Sierra to Catalina, but was automatically bumped up to Big Sur. Since a programI I regularly work with is not supported by Big Sur, I decided to downgraded to Mohave. I did so during a screen share with an Apple Pro advisor. The downgrade involved a clean install through the disc utility. Since the clean install would wipe out my data, I backed up my system to Time Machine on an external HD. I rebooted through the Time Machine drive. When I opened QB it automatically loaded 2 years of memorized checks, but all of the entries after 11/14/18, were missing. My back-up files are automatically stored to my iCloud Drive, but none of the back-up files dated past 11/14/18. It could be, that the files are gone for good, but before I accept that loss, I need to explore all options to find them. None of the ProAdvisors I contacted offer support with the desktop version of QB, and I believe  this will require more help than I might get in an online forum, such as a screen share to help me locate, not just the right QB.dmg, but the attachment that goes with it. PLEASE LET ME KNOW IF THERE IS A PRO ADVISOR THAT MAYBE ABLE TO ASSIST. In the meantime, I am attaching a screen shot of the Back-up files in the iCloud Drive and my documents folder.

Thank you for your kind attention~

Danuta

ps: I was not able to attach the intended files

Thank you for responding to my question. What I didn’t mention in my original post were the circumstances that led to the data loss. Last month I attempted to upgrade from High Sierra to Catalina, but was automatically bumped up to Big Sur. Since a programI I regularly work with is not supported by Big Sur, I decided to downgraded to Mohave. I did so during a screen share with an Apple Pro advisor. The downgrade involved a clean install through the disc utility. Since the clean install would wipe out my data, I backed up my system to Time Machine on an external HD. I rebooted through the Time Machine drive. When I opened QB it automatically loaded 2 years of memorized checks, but all of the entries after 11/14/18, were missing. My back-up files are automatically stored to my iCloud Drive, but none of the back-up files dated past 11/14/18. It could be, that the files are gone for good, but before I accept that loss, I need to explore all options to find them. None of the ProAdvisors I contacted offer support with the desktop version of QB, and I believe  this will require more help than I might get in an online forum, such as a screen share to help me locate, not just the right QB.dmg, but the attachment that goes with it. PLEASE LET ME KNOW IF THERE IS A PRO ADVISOR THAT MAYBE ABLE TO ASSIST. In the meantime, I am attaching a screen shot of the Back-up files in the iCloud Drive and my documents folder.

Thank you for your kind attention~

Danuta

ps: I was not able to attach the intended files

I hear you and realize the importance of being able to retrieve your transactions, @Danuta.

To help run a remote-viewing session and locate the said data, I suggest reaching out to our Customer Care Team. This team is capable of finding your lost data and verify the root cause of this matter.

Here's how to reach them:

1. Click on Help at the top.
2. Select on QuickBooks Desktop Help. 
3. Press on QuickBooks support. 
4. Choose your preferred way to speak with our representatives.

Moreover, if you need assistance with ProAdvisors, you can look for them through this link: Business is better with a ProAdvisor.

Keep me posted on how the conversation goes. I'll be around to assist you if you need more here. Keep safe!