I own a retail store and have never been able to prove but suspect someone of stealing if I refuse service to him can i be sued for anything?

As a general matter, you have the right to refuse service to anyone, as long as you do not make your refusal decisions on the basis of race, religion, national origin or any similar basis prohibited by law. You should obviously make no statements to anyone regarding the reason why service is being denied. You may lawfully exclude him from your premises but you are likely not privileged to use force to do so. Anyone can sue anyone for anything.