Z Axis Problem

Attached is my Marlin firmware file

Currently running RAMBo electronics on a Prusa Mendel. All motors were operational for the last few days. No major changes made to anything. Z axis motors just stopped working. The motors vibrate and make a high pitch sound but refuse to fully turn. Tried in Ponterface and Repetier Host. In Ponterface they just vibrate but do not move. In Repetier the motors move a little in each direction but vibrate a lot while emitting a sound but never moving the full amount. X axis motor and Y axis motor are still functioning properly. The firmware was not changed between working and not working moments. I have 3 mechanical endstops if that means anything.

This is my first printer! So I have no idea what is wrong... Please help!

I had this exact same thing happen to my Z axis when I had a bad solder joint on a Y harness for the Z axis, I'm using a Printrboard. I looked up the RAMBo board and it looks like it has two seperate connectors for the Z axis motors so if they are both acting up this probably isn't the problem. I just though I'd tell you that a bad solder joint on a cable can produce the problem you are describing.

I don't think the .ino file is of any use without all the other files.

Have you tried rechecking Vref?