Pc is not turning on.

Please help me. i have a pc and i had just installed windows 8.1pro 32bits on it and it has a partitiod disk space of 10GB. The total hard disk space is 320GB i also installed windows 7ultimate32bits in the partitioned 10GB disk in the same hard drive and last week i wanted to change the operation system in a hurry i was supposed to play songs from in the windows 8.1pro operating system and it was in the sleep mode . I had switched on the pc and it brought up the sreen lock. I hard not switch it off because i was in a hurry and i instead false turned it off by pressing and holding the power botton and when i switched on it start even now but does not go point the the dark screen that shows the dash thing( _ ) or (-) and it blinks three or four times then restarts up to the same point (-) and then goes off again then starts over again contiously. Please help