If Word documents are opening in Adobe Acrobat or another incorrect application, the Windows file association has probably been changed.
You can restore Microsoft Word as the default application.
Right-click a Word document and select:
Open with > Choose another app
Select:
Microsoft Word
Select the option to always use Microsoft Word for this type of file, then click OK.
The document should now open in Microsoft Word.
If Other Word File Types Are Also Affected
Word documents can use several different file extensions, including:
.docx - Standard Word document
.doc - Older Word document
If necessary, repeat the process for each affected file type.
You can also change these through:
Settings > Apps > Default apps
Search for .docx or .doc, then select Microsoft Word as the default application.
Changing the default application does not alter the document itself. It only changes which program Windows uses to open it.