My screen is scrambled while reading some unexpected chars,

It happens in a local tty, so logging out won't help.
Any ideas? Hopefully I don't have to reboot
Either type reset at the prompt, or if it's a graphical terminal it probably has a menu option to reset the terminal. If it's a virtual terminal then restarting the getty process providing the terminal will accomplish the same thing.
What happens is the terminal got stuck in "alternate character set". So it just needs to be reset to normal state.
reset works in a terminal emulator as well ;-P
Ctrl-lorresetdoesn't work, you could trysetfont...setfontdoesn't work,resetdid the job