Volume indicator bar missing

Sorry this is on the Alienware board - there isn't one for Precicion laptops (no idea why) and I have seen chargers etc. saying they work for Precision and Alienware so I'm hoping there is some similarity!

I hope someone can help with this. I have a Dell Precision M6700 which has been great until recently when the headphones socket started to become unreliable. As an alternative I needed to use a sound input/output device on a usb socket (it was a Scarlett 2i2). The laptop did not recognise the device when I plugged it in until I 'disabled' the onboard speakers/headphones device - then it worked fine. Once finished I removed the sound i/o device and re-enabled the onboad speakers/headphones. Since then the volume bar (that used to pop up whenever I used the dedicated volume buttons to change the volume) no longer appears. Looking at similar threads I went looking for a Quickset.exe programme (not on my laptop) or download (not listed on Dell downloads for this laptop) ... so I couldn't solve it that way. The volume indicator in the tray works OK but that's too awkward to use in a theatre when I need to check volume changes quickly. Any suggestions, anyone?