If you forgot the admin password, you'll need to upload a new firmware to the phone in order to get default settings again.
I first downloaded snom200-3.56z-SIP.bin from http://www.snom.com/firmware.html to my tftp server.
then I created a symlink snom200.bin to snom200-3.56z-SIP.bin
now you need to power on the phone. while the initial text/logo is displayed, press any key. the phone now prompts you for an ip address and a tftp address. enter these, and press OK. the phone will now update it's firmware and boot. you then need to select the country, timezone etc. once this is done, you get a new firmware with factory defaults.
now just point your browser to the snoms' ip address. (while we are here we can check if the bootloader can be updated too)