How Can I Fix One Drooping Eye?

There are many reasons for uneven eyelids from uneven excess skin to uneven brow position, but when I hear a patient say my eyes were not always even and then become more uneven after wearing contact lenses, 9 out of 10 times it's because of lid ptosis.
What happens with some contact lens users is that the contact lens rubs against the back surface of the upper eyelids causing inflammation which then causes the eyelid muscle to slip off it's normal attachment. The solution to do a small out-patient surgery repair to correct the lid ptosis. Typically it takes less than 15 min and can be done under local anesthesia. The incision is hidden on the undersurface of the eyelid so there are no visible scars. Stiches come out one week after surgery. It's really quite a quick procedure with minimal pain and minimal downtime.

There are various causes of uneven eyes. The causes can include eyelid, facial, and/or orbit abnormalities, which they in and of themselves could be due to various causes. The treatment would depend on the cause. 
You shouldn't necessarily assume your contact lens history is the cause of your problem, especially because your history doesn't really explain your findings. You should see an Oculoplastic surgeon and Ophthalmologist for a complete evaluation.

Drooping of the upper eyelid itself is known as ptosis. In many cases, upper eyelid asymmetry is related more to brow differences or asymmetries of the surrounding soft tissues than to problems with the lids themselves.
An in-person exam would be needed to give an accurate diagnosis and treatment recommendations.
Best,