I assume you are talking about a New Beetle (water-cooled, not air.) If so, if the cables/regulator let go inside the door, the best bet would be to install a kit that is sold at the dealership to upgrade the original plastic clips to the newer, metal backed style clips. The original ones were a poor design which would break and cause the window to a.) get stuck in the up position, or, b.) go slamming down into the door when you are driving down the road. you do need a special tool to install them, and I just so happen to have said tool (for me to use, not a loaner). If you just order a new regulator, all the ones I've seen that come new still have the old style clips on them.
The retrofit kit replaces the clips and damaged cable on the broken side and also has the clips to upgrade the opposite door.
Let me know if I can help.