Level sequence doesn't play

Ever since I made the level sequence for a level, it always started working right away. And it has been working for a very long period of time. Yesterday it just stopped playing when I started the level, instead it goes to the next node and executes that. I’ve checked the cinematic camera actor and tried playing the sequence, and it plays the Level Sequence when I pilot or preview it. The problem seems to be that there’s no render in the level sequence editor, as it would usually show the frames here:


I don’t know how to re-render it.
Please help.