@Nabil4
Headphones on a desk and a dispute over a duvet cover do seem like small reasons to accuse you of violating terms and conditions. However, I think there is something more going on here.
You say that Airbnb took one guest's word over yours and all of your other guests, but I doubt that is true. I have had a look at your listing and reviews and your lowest star rating is for cleanliness. I think it's 3.5 which is actually rather low. You should be aiming for as close to 5 as possible and Airbnb will treat anything less than 4 as failing to meet their standards.
While a few of your guests mention your place is clean in their reviews, just as many bring up cleanliness as an issue and, judging by the star rating, there may be others who haven't mentioned it publically but have down rated you in that category.
Thus, it's quite likely that Airbnb based their decision on all of these factors.
The room looks fairly clean in your photos, but it's difficult to tell if there is dust or if the carpet has been vacuumed, which another guest complained about. However, I can see that the window needs cleaning. Not sure if there are marks on the walls or these are just shadows. By headphones, I think you mean earphones, and I would also be grossed out if a pair of used earphones was left in my room.
RE the bedding, the duvet covers may well have been freshly washed, but are you sure there were no marks on them from previous uses that hadn't washed out? Sometimes bedding can just look dirty because the colour is not pristine anymore, e.g. if you have been washing whites with coloureds. Also, have you finished making up the bed in these photos as there don't appear to be any pillowcases?
Sorry, I am not out to criticse you and perhaps you feel your levels of cleanliness are sufficient given the price you are charging. However, I think guests still expect cleanliness in any price range and, unlike location, this is one category you DO have control over.
I always clean the rooms thoroughly between each guest regardless of if they were cleaned thoroughly two days before and on first sight still look spotless. They get dusted, polished, vacuumed and mopped again anyway (including light fittings, window frames, under the bed and the other furniture). Otherwise, it's easy to miss something, e.g. a used cotton bud left under the bed, which could be off putting to a guest. Plus, it only takes a day for dust to settle. I also have cats (three of them) so need to make sure every stray bit of fur is vacuumed up. This is why all three listings have 5 stars for cleanliness.
I would suggest that you take on board the feedback from guests as several mentioned that the cleanliness could be improved and they can't all be wrong.