I am 20 years old and I want a mid face lift, is this possible? How much? Can this also help change the shape of my eyes?

Hello,
At your age it is highly unlikely that your problems are due to the effects of gravity. By definition, this is what is addressed with a mid face lift (or any lift for that matter).  It is expected for every patient to have facial asymmetries.  Without photos it's difficult to give recommendations but I would recommend starting with something relatively inexpensive and temporary like a facial filler.
Regards,

Without pictures, it is difficult to guide you in your research of procedures that will help. At your age, I would recommend exploring volume replacement with fat or filler.  One of the first components of visible facial aging as well as significant asymmetry is volume loss/deficiency. It's important to have an in person consultation with a few board certified physicians who specialize in facial plastic surgery and perform a wide variety of both surgical and nonsurgical procedures on a regular basis.  They should be able to help you understand your facial aging pattern as well as the appropriate treatment options. Do your research and choose someone with whom you feel most comfortable based on qualifications, references, reviews, and seeing multiple examples/pictures of their work.  

probably better to consider fat transfer to your cheeks, allograft or cheek implant or implants. See a board certified ASAPS plastic surgeon in consultation. Good luck....