Grayson Martin

Umm can somebody please help me downgrade my Tekkit server to 3.1.2? My server crashed and my and my friends spent like 8 hours on the server and we need help.. I need to downgrade the serve cause I got this.. java.lang.NoSuchMethodError: buildcraft.api.PowerProvider.receiveEnergy(I)V at buildcraft.energy.TileEngine.q_(TileEngine.java:126) at net.minecraft.server.World.tickEntities(World.java:1189) at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:559) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:457) at net.minecraft.server.ThreadServerApplication.run(SourceFile:492) and I dont know how to fix it please help!