Libreoffice on computer; old file says can only be opened with microsoft office. how to open?

I purchased this hp desktop pavilion in 2014. At the time, my old files were transferred in. Libreoffice was part of the new computer. Now, as I try to open a document from 2012, the computer says it can only be opened with Microsoft Office. Is there any way around this, or must I purchase MS office (or submit to the one month free trial).
Seems a waste to have to entertain using MS office for one small document.
Suggestions?

Try one of these: First start LibreOffice. Then use menu File, item Open to open the document, or click on the item Open File in the start center, or drag the file onto the LibreOffice title bar.

If Regina’s suggestion works, then you can change the file associations in Windows such that LibreOffice opens your files.

Use your favourite search tool to find instructions for whatever version of Windows you are using.