With a lack of details I only assume you mean the gearbox mount has failed? and not that the gearbox has departed company with the engine!! if it's the first then a relacement mount can be quite easily be fitted but if it's the later you might of damaged the clutch,gearbox input shaft and selector linkage's. More info needed for a definate answer like vechicle age and engine size and type
nigel
October 2008