I played football in Europe and got paid in cash and I amended my return, and IRS is asking for documents but I don't have any documents, what do I do? Thank you.

You can try the TurboTax Audit Support Center (probably will not help much if you need documents).

See https://support.turbotax.intuit.com/irs-notice/audit-support/

 does the notice ask for anything specific because it usually gives the taxpayer an idea of what to send.  

if mot, about all you can do is call the number on the notice.   explain the situation and ask them what they want to see.