* Child Safety Locks: This is the most common cause. Check if the child safety lock is engaged on that particular door. There's usually a small button or lever on the edge of the door, near the rear.
* Broken or Disconnected Interior Door Handle: The handle itself might be broken, or the linkage connecting the handle to the latch mechanism could be disconnected or broken. This often requires removing the door panel to inspect and repair.
* Worn or Damaged Latch Mechanism: The latch mechanism inside the door may be worn out, jammed, or broken. This is a more complex repair, potentially requiring replacement parts.
* Cable Issues (Interior Release): The cable that connects the inside handle to the latch can stretch, break, or become dislodged. Again, accessing this usually means removing the door panel.
* Power Window Regulator Interference (If Applicable): If the window is electric, a malfunctioning window regulator could be jamming the door mechanism. Try operating the window fully up and down to see if this helps.
* Door Binding: Something might be preventing the door from opening, like the door being slightly out of alignment, or something obstructing its movement (like a mat or object caught in the doorjamb).
Troubleshooting Steps:
1. Check the Child Safety Lock: This is the easiest and most likely solution.
2. Try the Exterior Handle: If the door opens from the outside, the problem is almost certainly with the interior handle mechanism or linkage.
3. Inspect the Interior Handle: Carefully feel for any broken parts or loose connections.
4. Remove the Door Panel: This is usually necessary to inspect the latch mechanism, cables, and linkage. There are many online guides and videos that show how to do this for a 1999 Chevy S10. Be careful not to damage the door panel.
5. Check for Obstructions: Make sure nothing is preventing the door from opening.
If you're not comfortable working on your car yourself, take it to a mechanic. Trying to fix internal door mechanisms without experience can lead to further damage.
