Computer cant reboot

Hello,
It all started with my pc switching off due to loose power cable while there was some work was doing.
Well when tried to power it, its just giving me 1 short beep tone and 2 long beep tones and it would not start. The two LEDs on the power switch (my pc is a compaq) showing that power is ON and the other for the system are all steady lit. The software on it is windows xp
On the key board, the number lock LED is flashing. Pliz Help am stuck.................................