I'm having trouble reinstalling a mod pack

[PolarBurr539]

My game of pixelmon kept closing every few minutes or so. It closed just like every other time, but this time the technic launcher didn't open back up as usual when the game closed. I opened the program again and it wouldn't launch the pixelmon game... I tried to uninstall and reinstall the modpack, but it isn't letting me reinstall. I keep getting the same pop-up and I don't know what to do with it. Please help me D: