Just to reiterate of what Derek Halman is pointing out correctly. Here are just a few of the things that could be wrong with your transmission. Best to get it scanned and narrowed down:
NO LOW GEAR (MOVES IN 2ND OR 3RD GEAR ONLY)
Cause 1. Governor Circuit Electrical Fault.
Solution 1. Test with DRBT scan tool and repair as required.
Cause 2. Valve Body Malfunction.
Solution 2. Remove, clean and inspect. Look for sticking 1-2 shift valve, 2-3 shift valve,governor plug or broken springs.
Cause 3. Front Servo Piston Cocked in Bore.
Solution 3. Inspect servo and repair as required.
Cause 4. Front Band Linkage Malfunction
Solution 4. Inspect linkage and look for bind in linkage.
STUCK IN LOW GEAR (WILL NOT UPSHIFT)
Cause 1. Throttle Linkage Mis-adjusted/Stuck.
Correction 1. Adjust linkage and repair linkage if worn or damaged. Check for binding cable or missing return spring.
Cause 2. Gearshift Linkage Mis-adjusted.
Solution 2. Adjust linkage and repair linkage if worn or damaged.
Cause 3. Governor Component Electrical Fault.
Solution 3. Check operating pressures and test with DRBT scan tool, repair faulty component.
Cause 4. Front Band Out of Adjustment.
Solution 4. Adjust Band.
Cause 5. Clutch or Servo Malfunction.
Solution 5. Air pressure check operation of clutches and bands. Repair faulty component.
NO 3-4 UPSHIFT
Cause 1. O/D Switch In OFF Position.
Solution 1. Turn control switch to ON position.
Cause 2. Overdrive Circuit Fuse Blown.
Solution 2. Replace fuse. Determine why fuse failed and repair as necessary (i.e., shorts or grounds in circuit).
Cause 3. O/D Switch Wire Shorted/Open Cut.
Solution 3. Check wires/connections with 12V test lamp and voltmeter. Repair damaged or loose wire/connection as necessary.
Cause 4. Distance or Coolant Sensor Malfunction.
Solution 4. Check with DRBT scan tool and repair orreplace as necessary.
Cause 5. TPS Malfunction.
Solution 5. Check with DRBT scan tool and replace if necessary.
Cause 6. Neutral Sense to PCM Wire Shorted/Cut.
Solution 6. Test switch/sensor as described in service section and replace if necessary.
Cause 7. PCM Malfunction.
Solution 7. Check with DRBT scan tool and replace if necessary.
Cause 8. Overdrive Solenoid Shorted/Open.
solution 8. Replace solenoid if shorted or open and repair loose or damaged wires (DRBT scan tool).
Cause 9. Solenoid Feed Orifice in Valve Body Blocked.
Solution 9. Remove, disassemble, and clean valve body thoroughly. Check feed orifice.
Cause 10. Overdrive Clutch Failed.
Solution 10. Disassemble overdrive and repair as needed.
Cause 11. Hydraulic Pressure Low.
Solution 11. Pressure test transmission to determine cause.
Cause 12. Valve Body Valve Stuck.
Solution 12. Repair stuck 3-4 shift valve, 3-4 timing valve.
Cause 13. O/D Piston Incorrect Spacer.
Solution 13. Remove unit, check end play and install correct spacer.
Cause 14. Overdrive Piston Seal Failure.
Solution 14. Replace both seals.
Cause 15. O/D Check Valve/Orifice Failed.
Solution 15. Check for free movement and secure assembly (in piston retainer). Check ball bleed orifice.
Does not look like a good job for a DIY'er unless you have the proper tools and knowledge. Again this is just to reenforce Derek's answer :-) best of luck to you.