i can't find my .iba file and i only have the .ibooks file and i need to edit it urgently!!! any help???

Finding a copy of your .iba file is really the only way to do what you want. You should have backups of your system, either Time Machine or a clone, if you are investing that much time in creating files. Are there any of those you can search?

Two suggestions,

First, have you looked in iCloud? I've sometimes had trouble finding things because I was looking in local storage and somehow the file got saved to iCloud.

Second, sorry if this is too basic but have you tried looking under File/Open Recent?

If this was one of the last few books you worked on it should be there.