Press and hold the YouView front panel power / standby button for 8 seconds, until the lights change then let go. Then just wait for the box to restart.
This Soft reset of the TV Box often works to fix lack of response to the remote control and other strange operating faults.
Or, when the hard drive isn't active do a Power reset. Power off at the back on/off switch or mains power socket, wait a few minutes and repower.
Let me know how you get on.
...you should be able to change channel using the + and - buttons on the front panel of the TV Box. But the remote control is needed for most functions. Looks like the TV Box has a terminal fail of not responding to the remote so will need to be replaced.
I've alerted the TalkTalk Community Team.
Please ensure your Community Profile Personal Information (Click here) includes your name, address, current TalkTalk landline 'phone number and an alternate number (mobile recommended). Add, then scroll down and save changes. The TalkTalk Community Team OCE will then be able to link to your TalkTalk service account.
...electronic component fails happen either early in product life or at end of expected life.
As the soft reset and power off reset haven't restored the remote control function there is one final thing to try which is a Maintenance Mode reset including a full factory reset.
More complex issues might require a Maintenance Mode reset of the TV Box (Click here). Read the instructions so you know what to expect, select your box model and when prompted on screen select Option 2 (Keep recordings) as a first choice.
If the Maintenance mode Reset actually fixes the remote control issue then restore the box settings and at the same time it's worth rebooting the router and any connecting powerline adaptors and check they've got green lights showing.
You'll need to reinstate a lot of personal settings, including parental control PIN if used, Antenna out back to On, Picture & Sound setup, Apps & player logins, Mobile devices reconnected for the TV Planner app and TV Guide (yellow button) hidden channels.
Any Watch lists and Scheduled recordings will need to be reinstated so make a note of these before a Maintenance Mode reset.
The TalkTalk Community Team will pick this up and if the box has failed will arrange an exchange.