Hi mamoniem,
Please look through our troubleshooting steps in the link below.
https://wiki.unrealengine.com/Troubleshooting_Launcher_Problems#Troubleshooting_Launcher_Problems
If the issue persists, could you create a report on AnswerHub and link it here? Make sure to post your dxdiag and any other info you think will be useful.
https://answers.unrealengine.com/index.html
Thanks,
TJ