Hello again and thank you for your reply. I apologize if my response was unclear, however, I didn't mean to indicate that your employer could legally terminate you. What I stated was that under those specific circumstances I specifically discussed, an employer may or may not be able to terminate an employee who is out on STD or LTD. You will have to sit down with a local employment law attorney who can go over the facts of your case in detail, specifically the FMLA and ADA reasonable accommodation issue with you, to see if perhaps your employer either wrongfully terminated you.
They can also discuss the repayment issue. However, it is doubtful that your employer's actions in wanting a repayment of medical bills is lawful. You would have had to be given advance notice of termination of coverage and then given your COBRA rights but declined to sign up for them, in order for your employer to be able to deny coverage to you for the time you still were employed up until they gave you notice of termination.
As for your salary, if you were receiving it as a result of being on STD or LTD, then no, they cannot recoup that. In other words, those are insurance policies that you had, whether you were employed anymore or not and so payment under those policies is guaranteed if you otherwise qualify on the basis of a medical condition. So, if you are talking about salary received under the insurance policies, they cannot recoup those.
As always, please feel free to ask for clarification, but when we are finished, take a moment to leave a positive rating so I receive credit for assisting you with these answers.