Define good evidence. Do text messages and emails qualify? Would this be considered small claims or civil?
Well, the BEST evidence would be a written and signed contract between the two of you stating the $12,000 was a loan and detailing the terms and conditions of the loan. Absent that, text messages and emails can be used to show an agreement was made for you to loan your friend the $12,000 and he was to repay you.
Without convincing evidence showing the $12,000 was a loan, your friend can argue that the money was a gift or that you were investing in his business. Of course, the friend should have some proof, too, to support that the money was a gift or investment.
The small claims limit in Florida is $5,000.
What county are you in, Jay_Globo?