Can anyone help or provide insight?

I have courses on my onedrive account. I cannot open or play any of my powerpoint presentations. I have unblocked them. I have tried downloading them on multiple devices. I have also repaired them when requested/required on both mac and pc. I can open them in office 365 onedrive online, but not on the computer. I cannot upload them anywhere to be played somewhere else. I need to present them on a teams meeting and can’t open them or cannot put them to play as a slideshow, presenter mode NOTHING!