What to do if I had a minor collision with 2 cars and just found out when the insurance adjuster called me that I don’t have collision coverage for my car?

Check your policy, your coverage declarations, and your invoice(s): if according to the paperwork, you should have collission and/or have been paying for collision, then either 1) the insurer will have to honor it, or 2) the agent will have to cover the cost of the damage, if he somehow caused the collision coverage to not be purchased, accepted, etc.

However, if the policy, declarations, and/or invoices show in writing that you did not have collission coverage and were not paying for it, then you have no recourse: the law holds people to the terms of written documents and agreements, and expects that people will review the documentation they receive and correct it if necessary. Therefore, if the paperwork from the insurer doesn't show any collission, you would have been expected to have read it, seen that omission and then have corrected it (e.g. called the insurer to find out why you don't have it; purchase collision, if you hadn't before; etc.). If you failed to do your part to make sure you have collission coverage and simply accepted a policy without collission on it, that is, unfortunately, generally considered your responsibility.

Since you did not have collision coverage at the time of the accident, you will probably be sued by the other two parties who were not at fault in the accident.  They will be seeking damages (monetary compensation) for property damage (cost of repairs to their vehicles).  In addition, if any of the occupants of the vehicles are claiming to have been injured, you are liable for their medical bills, pain and suffering (an amount in addition to the medical bills) and wage loss.

If the parties obtain a court judgment against you which you cannot afford to pay, it would be advisable to file bankruptcy at that time.