CPU/Monitor is not detecting Window XP

Hello,

i have CPU of LG, I was installing window XP and during installing windows XP, CPU asked for restart but after shutting down it didnt start and Monitor showing Logo of LG only. it is not even showing BIOS setting. I removed CPU and Monitor connecting wire then Monitor Screen is Showing NO SIGNAL and as i Connected CPU and Monitor through wire again it is showing LG logo. Since than i have turned off and started Monitor and CPU many time but Monitor Screen is showing LG Logo of CPU only.

Plz help, what to do