Minecraft – Is the seed for a minecraft world stored in log files

If you go to your minecraft saves folder (usually something like C:\Users\%username%\AppData\Roaming.minecraft\saves) there will be a folder called players.

Go into that folder and delete the file with your name on it, and the next time you enter the world it should spawn you close to 0,64,0 rather than the extreme location you teleported to. Note that you will lose any items and experience you currently carry.

An alternative solution is to use a third party program like MCedit to edit your .dat file and change the location in the file. I'm afraid I don't know much about those though.

There are several types of world corruption - in some cases it just means that invalid entities exist in the game or the save files describe an impossible game state at some local point.
In your case the nbt format of the files themselves seems damaged, making recovery much more difficult.
The only way to restore your world that I can think of is creating a new one and then copying your region/DIM1/DIM-1 folders into that new save file (the region files seem undamaged). This would restore the areas you explored, but might lead to sharp cliffs where your pre-explored area ends.

edit: it seems like mcedit 0.1.7.1 (couldn't try newer versions) can open the world just fine. If simply copying the world didn't work for you, you could try loading it with mcedit and then saving it again.