Minecraft nether portal has stopped working?

I play Minecraft on my ipad (version 1.16.210). Since yesterday my nether portal has stopped working in a certain world. I can no longer come back to the upper world from the nether. If I go through in the nether, I'll stay down. I've put a lot of work into my upper world and want to go back. I'm only in creative mode so I can't die. In my other worlds, the nether portals still work perfectly. Can someone help me please?!

Hm first if you want to get out do / kill then you are dead but in the upper world and I would just build a new one maybe a bug or something