There are a number of reasons you are experiencing the numbness and tingling. The most likely reason is due to a nerve compression problem, either because of a spinal problem, peripheral neuropathy
which can be caused by a number of reasons included diabetes, electrolyte imbalance, thyroid
disorder, sciatica, decreased blood circulation in your leg, etc.
I recommend that you be seen by your physician for further workup. You will require some blood tests: CBC, BMP, Thyroid function tests, HBa1c. You will also require some imaging studies including x-ray of the spine and legs with possible MRI, doppler ultrasound, and maybe a nerve conduction study. Treatment will depend on the cause of your symptoms.
In the meantime I recommend that you take a daily multivitamin, drink plenty of fluids, and try to exercise as best you can (especially stretching).