Can anyone tell me plzzzzzzzz............?

They don't really "reinstall" it. Every mobile phone comes with a set of built-in applications, ringtones, etc. - sometimes even a whole operating system. These are written in the read-only memory of the phone - they can't be deleted or modified by the user.

When the phone becomes badly messed up (usually - because the user has installed some faulty or malicious applications on it), what the repair shop does is "restore the phone to factory settings" (or "format"). This basically means deleting everything the user has put on the phone. On most phones there is a special keyboard code for performing this operation.

If your phone has indeed been infected with a virus, it means that it is running the Symbian S60 R2 operating system. See the link below for instructions how to format such phones yourself.

To the other answerer - yes, there are malicious programs (malware) for mobile phones running Symbian S60 R2, Symbian S60 R3, Symbian UIQ, Windows Mobile and PalmOS operating systems. However, only Symbian S60 R2 phones are really plagued by viruses - there are hundreds of viruses for this environment. For the other environments only a handful of proof-of-concept viruses and Trojan horses exist and they are not a real threat.

what the heck phones can get viruses??? yeah i don't know....