broken shimano ultegra left shifter

hi guys, my flight deck left shifter suddenly stopped working. moving either sticks does nothing, no clicking nothing even attempting to catch.Has anybody had any success with repairing the shifter is it even worth me trying, I'm hoping something has popped out or vibrated loose and looking for a bit of advice on if I should even attempt dismantling the shifter, looking on websites I could be paying anything from 60 quid to a ton fifty to replace ( second hand and new) so thought I might just have a dabble, no tech experience changing an inner tube is about the total sum of what I have done before, cheers.

Billy