can I return at this walmart if my receipt was lost?

Yes you can.

Yes

If you charged it to a credit card? Yes.

Yes, but they may ask for id, I agree with the last comment as well

It also depends if it is electronics, or expensive, it is best to have your receipt & or the box or wrap that it came in.

Yes but will need id

Definitely

Yes, but you may receive a gift card as the refund.

Yup