Hi Sohym
This is Tamal trying to help you with the issue.
The model of the PC you are referring to is ages old, almost 13-15 years!
It could be ageing hardware causing the error, lowest costing issue could be the internal batteries not holding charge causing BIOS to fail retain its settings. A $1/2 (half) coin size battery replacement followed by BIOS settings modification (no cost) may bring it back to life.
Costly issue may be the hard drive needs replacement. You may take help of a PC technician to assess the current situation & if any hardware change is required or not. If the PC is associated to some special memory then may repair it else go for a new hardware.