MyStart.com is a browser hijacker that takes control of your web browser and change its settings:
Modify the default homepage.
Modify the default search engine.
To get rid of MyStart follow the below procedure:
Via the Control Panel
Go to the Start menu.
Open the Control Panel > Programs and Features
Uninstall the following programs:
Remove MyStart Search from the startup programs
Open the Run tab.
Type the following command: msconfig
Go to Startup tab.
Malwarebytes' Anti-Malware is a cleaning program that can help removing malwares. After downloading and installing Malwarebytes, click the "Updates" tab and run "Search for updates". Then, launch a full scan and click "Show results" after the end of the scan. Check all detected items, then click "Remove Selected". Reboot the PC, if asked to.
AdwCleaner by Xplode
AdwCleaner is a software created specifically for cleaning adwares. Launch AdwCleaner and click on Remove. You will probably need to reboot the computer after the scan.
Clean your web browsers
Remove browser extensions:
Firefox: Tools > Add-ons > Extension tab.
Google Chrome: Click on the Settings menu> Tools / Extensions
Remove the MyStart toolbar, Feven and any other parasites extensions.
Set your homepage and search engine.
Avoid getting infected again
You should be careful when installing free programs, as many of them are bundled with PUPs.
Read the EULA/TOS before installing softwares and always download programs from official sources.
If you are using Avast! or AVG, enable the detection of PUPs.