About an hour ago, I registered my question cisco 2811.
It is perfectly solved thanks to your comment!
However I have another cisco router, 2801.
A week ago, I forgot my password. so, I pushed the Ctrl+Break, and I entered ROMmon mode to recover my password.
And I did password procedure following steps which was followed in CISCO site.
Thus far it's OK.
BUT after I entered in console mode again, not ROMmon mode, I didn't perform "write memory" command.
After that, I turned router 2801 off and turned it on...
But it was not working from now.
The problem I saw was same thing like 2811 problem.(broken font, not respond)
In the same manner, I tried to fix it following steps ; change console speed more than 9600, 12800, 14400, 38400 and so on ↑.
But it was not working properly.
It still activated BROKEN font or Not responded like below photo.
Please ask me solution again...!
If the 2811 is now working, connect the 2801 to the 2811 ethernet ports. Get the 2811 to dish out DHCP to the 2801.
See if the 2801 appears in CDP.
This exercise is to determine if your 2801 is working or not.