hey hun

if you don't find it it is not the end of the world ... as long as you contact the renter and explain what has happened so they can cancel the check and write you a new one. I am sure they won't mind!!

the only thing i would be worried about would be if it was for cash/able to be cashed easily (i am not sure what your system is in the US) and someone found it.

just take it easy and if you can't find it decide what to do from there. things happen!