you probably heard that DHT (main cause of Male Pattern Baldness) is made from free floating testosterone by the enzyme alpha-2-reductase.
Propecia removes about 70% of DHT by blocking one of the two ways that alpha-2-reductase is made. Noticeable hair growth isn't often seen for about 6-8 months, with shedding and temporarily less hair. About 1 in 8 men, propecia doesn't help. Rogaine is also used to keep your hair from going into telophase (where the hair falls out and grows new in a couple of months). Visually it acts like propecia, with the initial loss and later increase.
Those two usually don't work in the front temple region (where I got my HT), but work well for up on top for those with diffuse balding.
It could also be other things, stress/infection/endocrine system issues.
I am no expert, someone else should be able to help ya more. Hope this star helps.