what could be done if your being told you owe money but you dont recall what for, a collection problem

Under the Fair Debt Collection Act, you can require the collections agency to prove the debt. They need to provide you with documentary evidence (such as a signed contract, a specific list with dates and places of services received, an invoice for sale of goods, etc.) both proving the debt exists and identifying it to you. So your first step is to send the collections agency a written request (preferably registered mail or some other you can prove receipt) asking for them to identify and back-up the debt.

After you get that, if it's a valid debt, you'll likely have to pay it, unless it's too old--every type of debt or potential legal action has what's called "statute of limitations" which tells how many years people have to pursue. The statute varies by state, by type of debt (for example, it's different for a credit card debt than a bill from a lawyer), and you also have to take circumstances into account, such as when the creditor learned you hadn't or weren't paying. So if it's a valid debt, unless it's to old, you will need to pay, though you will likely be able to negotiate some discount or reduction if paying the debt in full would be difficult for you.

If it's not a valid debt--no matter what the evidence, you just don't remember it and don't think it's your debt--you can dispute it. Tell the collections agency you are disputing the debt and find out if you need to dispute it with the original creditor or with the agency (if the creditor sold the debt to the agency, you'd take it up with them). You'll need evidence of your own however, to back up your dispute.

For a large debt, you'd probably want to get an attorney to help you dispute; if the debt is less than $500, it's probably better for you dispute it yourself. Just make sure, again, that you provide whatever evidence you can and ALWAYS keep good notes and all correspondence from your dealings w/the the collections agency.