If i bought a carseat and had the receipt but not the box it came in can you still return it?

Call the store to find out. Each store has there own policy on returns.

Rule of thumb you can check with the store to see if they can take it back. A lot of times they will ask you to bring in the store before they can or cannot accept it.

I really don't know, but you might try it. I know in the past they have taken back items that were even used, so give it a try.