How do I record an expense for something that was purchased that wasn’t linked to a business credit card or checking account linked to QuickBooks

hello Let me see if I can help.  First how was it purchased? Cash, Barter, ??  A  general journal entry would work but you would need a gl account- ie income account - barter.  If you paid cash.  Reimburse yourself with a check and note who you paid and date of your receipt on the memo line.  Cash the check and you are good to go with your cash back in your pocket.