Welcome to the forum.
See
[Tutorial] Format error discovered in sub-document for instructions on repairing the file.
If you want someone to repair the file for you you will need to upload
the original file before you sent it to the file converter to a fileshare site somewhere. The file conversion almost certainly truncated the file at the location of the first error and all content after the error will have been lost in the
converted file.
Or see
[Tutorial] How to find and un-delete AOO temporary files for
a) detailed instructions on how to recover your file as it was when you last opened or saved it, or as it was when it was last saved with AutoRecovery;
b) how to find previous versions of the file in the folder it is located in, but which have since been deleted;
c) how to un-delete the temporary files AOO wrote while you were editing the file, and then deleted. This will recover your file as it was when you last opened or you last saved it and is probably your best hope.