Can you sue your employer for not giving you your job back after returning from disabilty leave?

That depends on what "disability leave" you took. If the employer granted you FMLA leave, then you must be restored to your old job (or a job EXACTLY like it) even if the employer must fire some one to create the vacancy.

If you were just off sick or injured, you have no right to your job back, unless found in a union contract. Employers own the jobs and hand them out as they wish - the job is not "yours", but theirs.