Basically, I have posted this exact same problem here months ago, but with not a lot of help. I came here to get help and I intend of leaving with a bit of some. Basically, I rooted my HTC One, turned S-On, and finally installed Cyanogen Mod. Everything was working for the most part. I remember being able to attach my phone to my PC and being able to transfer files over to my phone. Recently that has been working out so well. I try to transfer files from my PC to my phone, such as music/videos/etc, but my phone doesn't show up. I can go to device manager and see my HTC One under other devices with the caution triangle, so basically my device is read to be connected to my PC but is lacking the drivers to use it. Like I said before, I have posted this problem on other forums before, and I have been sent the link to the drivers. I've installed HTC drivers, USB drivers, HTC One Sync, and so much more, but none of that has worked. All that happens is that my phone will connect to my PC, charge, be noticed by the PC but is completely unusable from PC to phone. On the phones side, it's 100% okay. No problems other than the simple nightly bugs, but I know it's the ROM version I am using. I reverted to the last known stable Cyanogen Mod, and the one previous to that. That hasn't fixed the problem as well. I'm running out of idea's and I'm just looking for some help. If you can help, rather then posting a link for drivers and thinking I'm retarded, please do so. I will appreciate it to the fullest. As for that, that is all I have to say. Please help, and all help is appreciated.