Hi,
Download an IOS image from the Cisco support site for the 2960 including the web based dev mgr:
http://tools.cisco.com/support/downloads/pub/Redirect.x?mdfid=268438038
Stick it on an http/ftp/tftp server on the same network or reachable from the switch.
Then use the following command on the switch to upgrade it:
switch#archive download-sw /overwrite http:///
Give the switch a reload and if required use the following commands to get http working:
switch(config)#ip http server
switch(config)#ip http secure-server
Cheers,
Ben