First you need to be able to itemize on your return to claim a contribution.
So if filing status is single, you would need at least $12,200 in mortgage interest, property taxes, contributions, etc. to be able to claim the contributions you made.
Click on below for more detail.
More details on Schedule A itemized deduction.
If you are able to itemize, you do not need the contribution receipt to file the return. I would document what you have said in the question along with some more detail, and then if audited, you can explain what happened.
I hope this helps.
