Disk boot failure.Insert system disk and press enter.

Dear expert recently i have procured a used pc.on 2.4.13 i was listening some music and video songs at that time i faced two times electricity failure and i keep off the pc.on 3.4.13 morning when i switched on pc i saw the subject noted message on the screen.i took help of expert and expert set up windows xp.3times the said expert faced disk boot failure.im anxious why such failure is occuring repeatedly.i would like to request the honble expert to show me the correct. way.Thanks in advance
1. someone tried to install xp? 3 times?

2. what is the make, model and model number of pc?

3. what does the disk say exactly?

4. what is the exact error message received when trying to boot up?

5. please provide the above information