Scrummy - I could have written your post, right down to have a 14m DD! Just like your's has always been a great sleeper, sudden switch a few weeks ago to waking more in the night,and then taking a while to settle at bedtime.
On Monday night, DD cried for 3 1/2 hours, standing in her cot. Just wanting to be cuddled. If you cuddled her, even if she had fallen asleep, she would wake up as you move and wail again. If you cuddled her while she was in the cot, this had no effect, the wailng just continued. Calpol - no effect. Eventually, I took her out and gave her a cuddle and she fell asleep and I was able to put her back into the cot.
Now, part of me is somewhat impressed by being able to stand for 3.5 hours, but mostly I was upset that she was so upset.
Hopefully, some of this was because she's been ill and sleepy and probably that day was just not very sleepy and all out of sync. However, to help this along a bit, we have started to put her to bed a little later, eg bath at 7.20/30 rather than 6.45 ish, and fingers crossed, this has helped. Lso, we are cuddling her longer so that she is asleep when we put her down rather than mostly asleep as before. This feels retrograde, like she's losing the self-settling, but she needs the sleep, so this will do for now.
So, other than delaying bedtime at bit, I have no advice, but lots of sympathy!