Since .62 there is only one language-file in the FBF, so for AVME you have to use .62, for AVM (german) you habe to use .65....
Get the .62 firmware and flash it via recover.exe...
ftp://ftp.avm.de/cardware/fritzbox.fon/firmware/english/
If it doesn´t work, try this:
First, use recover.exe to flash the last working old german/english firmware
*do not reboot after it is done*!
second, type "ftp 192.168.178.3" in the dos promt (IP shoult be the one discoverd by recover.exe). As there wasn´t a reboot after transfering the image, adam2 is still listening at the ftp-port.
User: adam2, password: adam2
Now you can type to switch your FBF back to german:
>debug
>quote SETENV firmware_version,avm
>reboot
After that, the Webinterface should work again.
See:
http://www.ip-phone-forum.de/forum/viewtopic.php?t=17498
After getting the old firmware back, I reseted default config, changed again via telnet to AVME. The old Firmware showed me the english frontend. I uploaded the english .62 firmware and it worked.