The result is my left nostril has no base left. Is It Possible to Reverse an Alar Base Reduction?

Sorry to hear about your asymmetry. I have not either seen or heard of reversal of alar base reduction. It is a very difficult to reverse, emphasizing the importance of doing it correctly the first time around.
There are a few surgeons who a very skilled at complete nasal reconstruction, Gary Burget, MD in Chicago one of them. They may be able to guide you to the best solution of your problem.
Dr. P

 It depends on the surgeon and how much is left of the alar floor. One would have to see it to make any opinion. See an experienced rhinoplasty surgeon who deals with many revisions.

Alar base reduction is performed to reduce a wide nasal base. If you have already had this done and it has completely obliterated that space, it is very difficult to bring in other skin. It can be performed; however, the skin has to be brought in from another location such as a flap or a graft, which will inevitably lead to scarring and formation of additional incisions.

It is very difficult to reverse the reduction once it is done. Depending on what you have now, it might be possible to put a combined skin and cartilage graft or do some local tissue rearrangement to increase the deformed side.
I would caution you that it will be extremely difficult to achieve complete symmetry. I have seen several patients from other doctors who had poor results from the reduction with an overdone reduction or a marked asymmetry. In all of these cases, after we discussed the pros and cons, and risks of then procedure, we chose to leave it alone.

Once an alar base reduction is performed it is extremely difficult to reconstruct the lost tissue and restore the original appearance. The magnitude of recontructing this would be like those that are performed for skin cancer patients. The scars are not great.

An alar base resection is performed by removing tissue at the nose's area where the nostril meets the cheek. This is a relatively simple procedure if performed properly and attention to the preexisting asymmetries that nearly every nose demonstrates. Certain anatomic boundaries need to be respected to ensure an attractive and natural result.
Unfortunately, once this skin has been removed, it can never be replaced. This places you in the category of revision rhinoplasty and potentially reconstructive rhinoplasty if insufficient tissue exists. If the problem could be solved by simply removing tissue from the other side, then you may have a shot at improving the symmetry. However, it sounds as if you would need tissue returned to the over-treated side. Skin or skin and cartilage grafts may need to be employed to correct this challenging problem.
Consult with several physicians (even via email/internet consultations), and ensure that you see someone who has considerable experience with revision rhinoplasty. It is the most challenging cosmetic operation around—best of luck.

Can not tell without seeing you. It may be possible to fix it a little but it can not be reversed. Once the skin is gone it is gone.

When the alar base is reduced it requires removal of tissue. If you want to reverse this procedure you will need to add some tissue back by way of a skin graft. This is something that would have to be seen to make a definite plan. Putting a skin graft back in this location is possible but the healing may cause more scarring than it is worth. A lot of this will depend on your skin color and how well you heal.
Best Wishes
Dr. Peterson

Alar base reversal can be done by taking a piece of skin from outside the alar rim , on the cheek and move that into the space where the rim use to be. The rime then fills the defect of the flap of tissue. 
On the plus side, the rim is wider. On the negative, scars can be bad!