some keys on my remote controller stopped working (i can’t go right and down). The others keys are working as normal. I can use my TV controller to go right and down but i would like to use only one remote so the question is : Is there a “compatible” remote controller or i have to buy the specific remote from osmc ?
You can use another remote, but it won’t be supported in an official capacity.
Have you tried re-pairing the remote and changing the battery?
Had you played around with the keymaps at all either manually or via the Keymap Editor add-on where you may have accidentally reprogrammed those buttons?
Although you can use a variety of different type of remotes with OSMC a key advantage to using the OSMC branded one is that it has been highly refined to the environment with both OSMC and LibreElec. Once you plug it it there are special modifications that load up in the background that tweak how it works so it operates more like a bespoke remote that would come with a standalone electronic device rather than a generic universal remote. Basically the tweaking and refining is done for you so it is a plug in and go type of affair. If you bought a similar generic remote likely you would have most buttons working and doing what you expected in most screens but to get better than that you would have a learning curve and a bit of a project on your hands to tweak it.