For an internal combustion engine to operate, compression should be somewhere in the range of about 130 psi to about 175 psi and no cylinder should vary more than about 10-15 % . Is a compression test the first test you are performing? How many miles are on your vehicle? Did it stall and not start or just not start? Inspect the spark plugs and see if any look different than the others. Has it been sitting for awhile or were you driving it daily? Need a little more information.