I came back to Canada after 12 years, and I apply for fingerprint to attend a school, and I got a criminal record saying that I had offense of theft under $5000 in 1997 and fine of $50.
I never had anything like that and never went to court
How this happened in court without my knowledge and evidence.
It is that possible to be convected without be attending the court and had my fingerprint.

Yes, if you failed to appear at trial, you could be convicted in abstentia. Or it could be a case of mistaken identity.

So you need to clear this up. It may require an attorney.