After installing ubuntu 12.04 through windows installer (wubi) the boot menu is frozen to windows7 entry. Keyboard or mouse doesn't work at all. Any solutions ?
If you're using a USB keyboard, it may not be available through the BIOS - and this affects the Windows boot manager as well.
See if you can enter BIOS using the same keyboard. If not, plug another keyboard using PS/2 connector (if applicable) and see if that works. See if there is a setting to enable USB legacy mode in the BIOS.