Driver seat does not recline - 1998 Ford Explorer

The seat isn't electric for recline? There are known issues with seats. If it is a manually operated seat, I would remove it and look underneath. It sounds like a broken spring or loose connection to a linkage.

https://www.google.com/search?q=toyota+solara+driver+seat+recliner+stuck

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Power Recliner
The driver seat has an electro-mechanical backrest adjuster. The backrest adjustment switch is located on the side of the seat cushion side shield and is part of the seat control switch. The recliner motor is mounted to the backrest frame. Power recliners and motors are only serviceable by installing a new backrest frame assembly.
Does yours have Driver and Passenger Power Seats Without Memory Or Power Driver Seat With Memory ?

B1666 Seat Driver Recline Motor Stalled On-Demand If the motor does not operate, Go To Pinpoint Test L . If motor operates, Go To Pinpoint Test M . Take it an have it check !
Does your

You do not say what design 3 series; but for E36 with electric seat adjustment, Odometer Gears (link below), makes replacement gears for the electric seats for approximately $40 each. This is the part that typically wears/breaks for seat reclining.
BMW-US E36 Driver's Seat Recline Gear/White
BMW-US E36 Passenger's Seat Recline Gear/Green
http://www.odometergears.com/products/BMW/3+Series+E36+90-00/26

to determine if lever just broke and seat works OK, actuate seat with vice grips to verify operation

It sounds like the inside of the recliner knob is stripped out. If you go to your local GM dealership and give them your VIN number they can order you a new one. Here is the removal and installation directions.
Driver or Passenger Seat Recliner Handle Replacement Removal Procedure

1. Use a flat-bladed tool to remove the plastic center cap from the center of the recliner handle.
   
   
2. Pull the recliner handle off the shaft.

Installation Procedure

1. Install the recliner handle on the recliner shaft.
   
   
2. Push the recliner handle firmly onto the recliner shaft until fully seated.
3. Install the plastic center cap into the center of the recliner handle.

Hope this helped please hit the accept button and positive feedback is appreciated.

seat recline motor stuck or unplugged

Someone will have to remove the seat and check the motor and linkage to see what is broken.

electric or manual?

usually not. seat is electric and adjusts to extent allowed by that. Passenger seat has a back release on it though.