First thing to consider is if you have a family history of hair loss, if there is male baldness in the family. In this case you will be more prone to similar problems. It may not recover very well with medicines.
Also change or residence, environment, water, diet is common cause for
hair fall and changes in growth cycle.
Other causes to consider are hormonal(thyroid etc), stress, any history of recent illness like typhoid, any chemical procedures, etc.
These causes need to be considered and treated as they affect hair growth.
If you are currently not an any treatment, you may apply
Minoxidil solution to scalp with hair supplements daily like
Keraglo Men. This needs to be continued at least for 2-3 months.
Do
consult a dermatologist as well, to assess your type of hair loss and to give you treatment based on the results. they may also suggest some routine blood tests if required.
Since medical methods do not work well for you,certain new surgical procedures can be considered such as PRP,
hair transplant or other procedures etc, as will be advised by your consulting doctor after observation.