Hello there my friends,
I've had the same problem. I tried anything, reinstalling java, reinstalling tekkit, installing older versions of java, ginving more ram to java, ect. nothing worked, but ive foud a solution. I got desprate, so I just reinstalled windows 10, and it worked.
To reinstall windows 10, go to settings, update & security, Recovery, click Get started, then keep my files, It will take some time, but it fixes the problem. Hope this helped!
Greetz,
~Semmie