Why won't Minecraft let me log in with my Mojang account? [closed]
Did you buy a legitimate copy or are you using a cracked version? This is a known issue with cracked copies of Minecraft.
If this is not your problem then there really aren't many other reasons.
- The login servers could be down.
- You're typing something wrong, recover your password just in case.
If these aren't the problem, then email Mojang. Also, check this site for info on if the servers are up: http://xpaw.ru/mcstatus/.