How will you remove this error “ ntldr missing press any key to reboot the system” ?

Reboot the system with XP, ( apply also on server2003,) cd
On setup screen press to R to repair the window
Now provide the administrator password
C:\>cd f:( your cd drive latter, f is taken as the example )
f:\>cd i386
f:\>copy ntldr c:\
f:\>exit
reboot the system

How will you test LAN card?

Ping 127.0.0.1 -t

If getting reply its fine

ESD wrist strap.

ESD wrist strap is used to protect a PC, the ground is often attached to the computer chassis.

A safety device used to channel static electricity to a proper ground while handling sensitive computer equipment. ESD damage occurs when a release of stored static electricity travels from something such as a person's body into a conductor of a different potential, such as a computer being repaired. The ESD wrist strap safely channels the static electricity to a proper ground, typically the computer's chassis.
An electrostatic discharge (ESD wrist strap may also be called an ) anti-static wrist strap.