Electronic – STM32F072 3.3V on UART with Wi-Fi ESP 8226

I don't know what to tell you, aside from the fact that you may have put the device into a strange serial mode (maybe you turned on an extra stop-bit, or set it to 7-bit serial).

I would recommend you try the configuration application that the manufacturer provides at the link about your module.

If that doesn't work, it looks like there is a mechanism for forcing it into a "configuration mode", which you can access by tying the nCTS/MODE/GPIO pin high (to Vcc), and restting the module (by connecting nRESET to ground temporarily).

From the manual:

In launching configuration mode, the system ignores the default work mode parameters, and force to operate in the AT+Instruction mode, this mode is commonly used to modify the parameters with the configuration management program and to do the function tests.

Look at section 4.2.1 in the PDF manual.

It's worth noting that if the module is correctly set up to join your network, it may be possible to fix it's configuration by connecting to it via WiFi. All the information about that should be in the manual.

I have fixed this problem, solution was to edit project configuration in MikroC IDE, there were few premade schemes that i tried and one of them worked, everything works great now.

Project configuration can be changed from Project -> Edit Project and there will "Load Scheme" button on right. There by default it will show you few premade schemes, select one for your microprocessor.