Can I sue if they deny?

actually your workers compensation benefits will continue regardless of whether you work for the company or not. If you were employed on the date of the accident, the workers comp will pay you your lost wages (up to a statutory max) plus all your medical care. If they fire you, you might be able to claim you can't do your job anymore and get permanent disability benefits but w/o a lot more information I couldn't tell you much more though you should see a workers compensation attorney (or if you were in a union, a union rep) who could answer all these questions for you for free.

You are covered by workers' comp. for injuries that occur when you are an employee. It does not matter if you LATER not an employee (if it did, employers could fire you every time you got injured and never pay workers' comp.). So the short answer to your question is yes: you are entitled to workers' comp., and you can sue if you do not receive what you are due. However, workers' comp. is often run through the state, or at least with heavy state oversight, so it is pretty unlikely that the employer will be able to stop them from paying out your viable claim.

You may have a separate claim against your employer for improper termination. Check with an employment lawyer.

You have worker's comp rights even after termination, but your termination sounds like the result of your carelessness about the workplace. How exactly did you get hurt? That may also affect the worker's comp eligibility.