how to restore phone backup? are we deleting any data from phone?

Posted by nikedue19
i am using sony ericsson k750i
and created a backup of all my phone and sim contacts, sms, sms archive
using my phone explorer 1.6.4

now when i restore the backup it starts deleting the data from phone
like contacts and smses

while restoring i stopped in between the process and found some of my contacts deleted from my phone...

may i know wht exactly are we doing while restoring???
are we deleting the data from phone???

please help me buddies!!!
waiting for ur replies...