My 1990 toyota celica won't shift in gear after I sart it.no matter How much I press the clutch pedal.If I start on gear , I can't shift to neutral. I change slave master clutch nothing. I don't see any leak around the clutch master cylinder. Please help..

The slave mounted to the side of the transmission is one thing. Is that what you changed?
And the clutch master cylinder mounted to the pedal is another thing. Did you change that too? Did you do both parts and bleed correctly? If not, go back and replace the master cylinder.
If so, then I'd say there's a problem in the pressure plate, clutch disc, or transmission shift fork.

Either there's air in the system, or, more likely, the clutch is worn out. A new Perfection or LUK Clutch Set, which includes a new clutch, pressure plate, pilot bearing, release bearing, spline grease, and alignment tool, costs around $115. They are not too difficult to install, provided you have the right tools.