If its the lower part of the engine which is the slum part how much will it cost me,ford focus 1999 model lx manual 5 doors

If it's the sump which is common due to rusting , it's not a major job . You will need a new sump / gaskets /seal , which you should be able to get cheaper from motor factors .Best to phone some local , independant garages and compare prices .Seen quite a few ,and done some with fibre glass , but usually not worth the hassle especially if you are keeping the car .