At the end of the second level of this game, Thailand, it occasionally happens that a lever doesn't appear which makes it impossible to proceed. In case you have already saved past a certain point, you have no other choice than to restart the entire game. The lever only appears if you have triggered a certain message earlier in the level.

About halfway through, you reach a big statue of Kali and Shiva. After dropping down to the bottom of this area, save, then head up the stairs on the right side first. Near the statue is an ornament with several crystals. Examine it to learn that one crystal is missing. Once you have done that you can continue as usual and the lever at the end of the level should be there. In case it isn't, although I have tested this several times and it always worked, reload.

Players who took the left path first and already collected the crystal from the ornament on the left side, won't receive the message of a missing crystal when they examine the ornament on the right side, thus the lever at the end of the level does not appear, making it impossible to proceed. While at first it seems that it is entirely random whether or not the lever appears, it's only a matter of some strange scripting in the game. So make sure to trigger this message, if you want to complete the game.