There is no need to do anything so drastic. If you have a regular, not
a 'restore' XP CD, Set the BIOS to boot CD before Hard Disk. Boot the
XP CD and, instead of Setup, take the immediate R for Repair. Assume
any password requested is blank, and TAB over.

Give the command
BootCfg /Rebuild

Or you can go to Control Panel - System - Advanced, click Settings in
Startup and Error recovery and there click Edit to load the file into
Notepad for editing. If it looks weird, clear out all its contents and
start over - it should look like

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOW S
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP"
/fastdetect

With the /fastdetect being at the end of the line starting multi(0) -
not wrapped round