All formulas replaced with Object 1, Object 2 etc after reopening a file

I opened a previous docx file with LibreOffice.

I saved a couple of times inbetween, although did not close the document. After I had finished, I just in cased saved it in different formats (odt, OpenOffice, docx ) as copies.

Although now the problem is:

None of the formats, even the original document does not display the formulas anymore. In LibreOffice they are all displayed as Objects. Object 1, Object 2 etc. In Word 2013, they have simply been deleted, blank spaces in the places where the formulas were before.

I have no idea what to do to be honest. I would like to know what could I do to regain my document. I spent over several hours on the document and I really do not have time to redo everything. Is there any way to gain the original document back, so that I would be able to print it out with formulas?

I apologise if I could not express myself clearly. I have not much experience with IT or the related terms and English is not my native languge.

Thank You