Cant find preinstalled engine in epic games launcher

Hi, previously i have installed the epic games launcher and also downloaded the engine version 4.15.And everything was fine i could launch the editor from the epic games launcher.But yesterday for some reason i had to format my c drive.but i installed the epic games launcher and the unreal engine version 4.15 in my f drive.now i can seperately launch the unreal engine editor.but when i run the launcher i cant find the installed version.

what should i do .is there any way to fix this
thanks

Hello DARKINFINITYSTAR,

Sorry that you are having an issue with the Epic Games Launcher. In order for us to offer the best support, we have recently modified the process for how Epic Games can help troubleshoot your Launcher issue. Please visit http://help.epicgames.com/ for technical support, here you can find information and solutions for common issues, as well as a contact form if you still need additional assistance. Thanks!