Nokia 3500c
Message problem

I do have nokia 3500c...

i purchased it before one year..

my problem is,

there is a message in my mobile which i couldnt delete...

Text shown in the message box stats as follows:

"picture"

but when i open this message the direct option available was

"delete"

instead of being as

"reply".

Actually it was a text mess which i deleted a long while ago...

i dont know why this problem occurs...

further i'm a airtel customer...

when i send message through this phone, i'm not getting delivery reports though my inbox and the entire phone memory is free... I don't used to send many messages...

when i rung and enquired about this to airtel customer care, they stated that there is no network problem..

further when i use some other mobile, i'm getting delivery reports for the same number.

this confirms that there is some problem with the phone...

Do i need to format my phone?

If so what is the problem in my phone and why this problem occurred in my mobile phone?