After "Your home bed was missing or obstructed" in minecraft, I can't find my way back

If it is a creative world, you most likely have not explored a lot of the land mass, which should make this a lot easier to find, but it should work in survival worlds as well.

By default, your chunks are saved in:

%appdata%\saves\<world name>\region\*.mca

By checking the file modify date, find the last file that was changed before you died, as this is the file in which your chunks are saved that you modified. You can then use the application named NBTExplorer to open the .mca file. After opening, you will see the chunks that are stored in that file. The formatting is as followed:

Chunk [<i>, <j>]    in world at (<x>, <y>)

<i> is the internal X coordinate of the chunk relative to the mca origin
<j> is the internal Z coordinate of the chunk relative to the mca origin
<x> is the external X coordinate of the chunk based on the game coordinates
<y> is the external Z coordinate of the chunk based on the game coordinates

By putting the <x> and <y> in a Coordinate Tool you can find the exact coordinates, or you can calculate the approximate coordinates yourself by multiplying the numbers by 16. (where 16 is the number of blocks in the X and Z direction of the chunks)

Please note that even only loading a chunk makes the game update the mca file.

You should have spawned near your original spawn point before you slept in the bed. go the general direction you went to build your house. If you remembered the X, Y, and Z coordinates, you could teleport there