encoding problem word excell

I have many word and excell files that were 'hit' by a virus i attach 2 photos of the error i get and an actual doc file 90% of the files are in greek. Also i have tried different version of office and didnt work also what i want is for someone to show me a way to resolve this,so i can do the same for the rest of my files in order to accept the bid,the buyer should provide a screenshot of my word document recovered ( just a few lines of course ) thank you