that´s not much info you give here, hard to say...
I suspect it´s MC 1.7.10 with the latest Forge ??
May be a corrupt Java Install ?
If you´re on windows try to use the embedded Java version which came with your Minecraft installation.
Change in the launcher instead of "C:\Program Files\Java\jre1.8.0_77\bin\javaw.exe" put "C:\Program Files (x86)\Minecraft\runtime\jre-x64\1.8.0_25\bin\javaw.exe" instead. Try if that works. Either use this version of Java or reinstall 1.8_77 again!