I too have sometimes lost my mojo - and felt very bad indeed, and very low energy. I found that, to rediscover my mojo, I needed to pay attention to what I was thinking, quietly, behind my other obvious thoughts. And then ask if these thoughts were really true - was I really no good at xyz, was I not likeable enough to bother people with talking about my worries, did I have energy to take on new things, and would it really be a disaster if I tried something and failed? It turned out that failing at e.g. water colours (I produced some really awful pictures) didn't matter - it didn't mean I was my very self a failure, and I enjoyed painting anyway. I could go for walks - that helped too. I could stop trying to hide from life and I could talk to people, and I re-discovered my mojo. I think Kipling wrote something like this, about feeling very down:
"When you get the hump, the Cornelius Hump,
The hump that is black and blue
Don't sit in the corner and read a book
Don't sit by the fire and stew
But go in the garden and dig and dig
And dig and dig till you are through"
You don't have to be a gardener - though I think that helps too. I found just that paying attention to my thoughts and behaviour, and then behaving and thinking in different healthier happier ways, changed my world.