If you still cannot retrieve the access to your MikroTik router or RouterOS devices after you tried to reset it to factory default settings, you can reinstall the RouterOS on your router with NetInstall to start everything from fresh.
NetInstall is a program that runs on Windows computer that allows you to install MikroTiK RouterOS onto a PC or onto a RouterBoard via an Ethernet network.
NetInstall is also used to re-install RouterOS in cases where the the previous install failed, became damaged or access passwords were lost.
First of all, you have to assign a static IP address to your computer, the method is different in Windows XP, Windows Vista, and Windows 7, you can refer to the following link and follow accordingly to setup for static IP, 10.0.0.1 and subnet mask, 255.255.255.0, leave everything else blank.
After that, you will see the properties as below.
The Network Connection Details as below.
You should disable any firewall software on your computer before proceed. If the following steps are failed later, you should disable all other network adapters (including Ethernet and wireless), leaving only the one you are using to connect to your router to be re-installed, then redo the steps from here onward.
Run NetInstall which you downloaded at the beginning on your computer.
Press “Net Booting” button.
Tick “Boot Server Enabled” and enter IP address, 10.0.0.2. Press “OK” to complete.
While your router power is turned off, hold the reset button and do not release.
Turn on the device power and keep holding the button even you find the USER LED labelled with “ACT” starts flashing.
After the LED stops flashing and turned off, you can release the button.
Wait for a few minutes for the MAC Address of the router to appear in the Routers/Drives list of on NetInstall.
Click on your router to select it under the list.
Press the “Browse” button on NetInstall and browse to the folder containing the downloaded firmware (.npk file) to install onto the router.
When you have finalized the installation parameters, press the “Install” button to reinstall your RouterOS.
When the installation process has finished, press ‘Reboot’ button in NetInstall to reboot the router.
After the reboot, you should get your router working with the latest RouterOS now!