Mega2560 cannot upload any program after having served as a AVR ISP

The first few days I used Mega2560 r3 for studying with example sketchs. I used on Win 7 64b or Ubuntu 13.10 64b and 1.0.5 r2 and 1.5.6 r2 of version Arduino software in any combination. Everything working fine. Today I used Mega2560 as AVR ISP to upload program to Mini, where I connected only Tx/Rx and 5vdc/gnd (4 wires). I upload ArduinoISP sketch to Mega2560 ( Programmer option changed in Arduino as ISP) and then I upload example Blink sketch to Mini board who is immediately began to work properly. I turned off the power supply(always over USB) for both board and apart wires between Mini and Mega2560. Then I tried to upload Blink sketch in Mega2560, but then it begins to be a problem - I cannot upload any sketch in Mega 2560. In Tools menu selected Board Mega2560, Processor Mega2560, ckecked proper port and in Programmer have been tried AVR ISP, AVR ISP mkII, USBasp. - I try with other usb cable and other usb port - nothing - I delete driver and device and install "new" ( I try on two different W764b and Ubuntu 13.1 64b) - nothing - when I push reset button, L led blinks twice and that is all. Bootloader is in, as I red on some topics. - I try to change port, restart app, and check new port - nothing - I try loop back test but nothing happend; I used Hyper terminal from Win7, 9600,8n1n - I try to upload sketch after push reset button in different intervals - nothing

This is a part of log :

avrdude: stk500v2_ReceiveMessage(): timeout avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] avrdude: Recv: avrdude: stk500v2_ReceiveMessage(): timeout avrdude: stk500v2_getsync(): timeout communicating with programmer avrdude: stk500v2_command(): failed miserably to execute command 0x11 avrdude: stk500v2_disable(): failed to leave programming mode

avrdude done. Thank you.

When I try burn bootloader, appear next text:

Using Port : usb Using Programmer : stk500v2 avrdude: usbdev_open(): did not find any USB device "usb"

Is there any idea who that would solve this problem? Thanks!