I would like to know if att will help me switch my sd card in phone to a bigger one for work.. Without losing everything??

Yes

Will they switch it over right in the store?? I have no computer and everyone I know uses their phone not computers.. I need someone to do it for me and I really don't want to lose anything

I'm not an IT expert but I believe it is possible and they certainly will help you with that, the staff is friendly and very helpful. However you should expect to wait a bit if you don't have an appointment.