I have cisco 2960 and have configured the timezone as mentioned below
sh run | i time
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
clock timezone CST -6
clock summer-time CDT recurring
I have changed the date and time manually but after reobboting the switch its going back to old date and time(feb 2003 )...
This is normal behaviour for a 2960 switch. The clock is not battery backed up so will always set itself back to the default when the switch is reloaded.
If you want to keep the time between reloads then you need to setup the switch as an NTP client and synchronise it to an NTP server in your network.