the formality or informality of your document is immaterial. What is material for your case to prosper in ourt is the substance of your document.

It must show the nature of your transaction, mentions the goods or money he received, his name and signature thereon, and any witnesses to the transaction.

If you parted goods or money based on his representations, and which you awfully trusted, and his promise or acknowledgement of paying you back, and he reneged on this promise, then you have a criminal case for deceit or estafa.