Unkown charge off on my credit report

There is a charge off on account on my credit report. Honestly, I dont remember the creditor, I’ve looked through my past documents and cant find anything with this creditors name. Now I do remember paying off an account for a car that i no longer have. I am not sure if this is the account. I tried contacting the bank that I used to do business at the time to see how can I retrieved a cancel check, since the bank account was   in 2002, they are telling me that they would need to try to retrieve those files and at the same time I would need a check number, in which I do not have. They also advise me that then if the account is retrieved I would have to pay $20 for every check that I wrote out for the year I believed that the check was written, advising that it would cost me anywhere from $1500 – $2500. Not worth it. The creditor has a charge off balance of $2153 and at the same time they sold it to a collection company that has a balance of $3200. How do I try to fight this? A lot of my old documents were lost in a flood I had in my home in 2003. Should I try to validate this account with the creditor and/or collection agency? and if so, and its validated should I try to work out some kind of payment with the original creditor since I do not have proof of payment?

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Dispute it
and
validate it
 
They must send you detailed documents with proof they own it and they can collect it.