I was working at a restaurant where people come work for couple of days and never come back for their cheques and things like that, I was going through a hard time and needed some money so I saw the opportunity with these cheques which were unclaimed for a while. So I took a cheque for $400 CAN and forged the signature of some girl and then cashed it, they found out about it and realized it was my girlfriend's account which I use to cash my own cheques since I don't have one of my own. They are investigating because I said I got my wallet stolen but I know they know it was me so I am just going to tell the truth but I would like to know in what kind of trouble am I in? Please someone help me, I am 23 with no criminal background or nothing and I live in Alberta.

Well if you stole a check ,forged someone name and cashed it,that is stealing plain and simple. That makes you a thief! I don't know about the laws where you are at but I can only guess you will be charged. Tell them what you did and pay it back maybe they will have mercy on you.

OK, this is not in the legal section, so I don't have to give you a direct legal answer.

You are a theft, there is no excuse and you most likely will only get probation and have a record, but with stealing from where you work, will find it almost impossible to find a new job now.

There is a outside chance, that now they will try and pin a lot of missing things on you, or if not, the judge may still go after jail time.

I would get an attorney before I did anything, of course they may arrest your girlfriend also, since it was her account you used, and she can also be charged

I assume you are in Canada. Canada classifies this as Theft under $5000. A first time offender can apply for a diversion that will leave you without a criminal record after completion of a probation.

If you want to admit it, first consult an attorney to arrange it.

Oh, and I've moved your question from the Banking forum since it didn't belong there.

Since you have no been charged, no police involvement.
I highly suggest you to do a apology to your employers, and promise that would never happen again, and willing to pay a fine with this mistake.
Otherwise, if they called police, you may be charged for both "fraud under $5000 and theft under $5000"
You will have no chance to get diversion since it is not a simple shoplifting, it is a fraud

I would forget about keeping the job. If I were your employer you would be out the door. The only question is whether there is criminal prosecution.