There is a very popular mod called mystcraft in which you can create worlds and dimensions however if you go into one without a linking book(whichc is how you get back) you are stuck. However there is a few ways to escape.

1: If you dont want to cheat, open your world to lan, have someone join you and have them make and ender chest, then make and ender chest for yourself and have them send a linking book through.(getting blaze powder might be hard)

2: There is a cheat that you can do, if you dont have cheats enabled then open the world to lan and enable cheats. The command is /tpx {your name} 0.

3: If your world has the page star fissures then there will be a few bottomless revines close to spawn that will take you back home. However they are extremely rare. Star fissures can natrually spawn but are still very rare

4: You can search for an end portal and go into in, defeat the dragon and go back home. Probably the hardest way but it is a last resort.