laptop keyborard and touchpad missing some inputs

I have a 3 years old ASUS n56vv laptop running Windows 10. When I use the keyboard, it happens that some keys are skipped. There are times when it happens frequently (like one character per word) and times when it just does not happen. The same happens (less often) for the touchpad. For what concerns the keyboard, could it be something not related with physical causes (like dust or keys wear)? I suppose that, in that case, the problem would occur more regularly and with specific keys.

I have the Asus N56V as well, neat thing, though have fortunately not (yet) had such issues.

Are the issues with the key presses consistent on the same keys or random in general. If the letters you miss are random I would start looking to make sure it is not some HID driver hiccup. Check your windows event system log ( ⊞ Win+X , event viewer, windows logs, system ) , look for a HID device being connected and disconnected.

Another possibility is performance hiccups, years ago on a different asus laptop I had a very similar issue, though the issue was more focused on random hiccups and stuttering, even in programs or games it would just stop entirely for half a second, it turned out there was a Asus 'bloatware' powermanager constantly writing a log file to a folder which, as the logfile grew over time worsened the performance hiccups. Narrowly watching my performance logs & graphs I managed to trace it and remove it. It might be worth checking your task manager for programs or services that have excessive spikes.

You could also try temporarily uninstalling any asus related software relating to your hotkeys and see if this resolves it.

As a little more "extreme" option you could try booting into an ubuntu live setup and see if the missing letters and input issues occur their too. (can easily install to USB using unetbootin, https://unetbootin.github.io/)