Re: One of my users can not access to do estimates today and was able to a week ago?
I've checked our records and didn't see any reported issue same as yours, Stacyb1. The user should be able to create estimates.
This is probably a web-cache issue. First, let's open QuickBooks Online using an incognito window to isolate it. From there, let your user create an estimate. If they're able to do so, let them go back to the main browser, and then clear the cache. It's a good idea to clear them out from time to time. This is to prevent the program from acting differently.
On the other hand, using a different web-browser resolves issues like this (Google Chrome, Internet Explorer, or Mozilla Firefox).
You can keep us updated after trying these steps. We're just around.