Is trekking alone safe?

I haven't gone on a single trek in the last year and a half, all because i haven't been able to get partners. I've been thinking of going for a trek alone (to Leh or Manali) but the am still confused. however, the frustration of not being able to go anywhere is maddening! Any suggestions for trekking in march or june next year??

really not a problem. All the regular advice says do not trek alone but that assumes you are going to the serious backwoods - most of us dont. Trekking in a lot of places follows village or shepherd's paths and if you turn an ankle there will be someone coming up the path in an hour or so. i backpacked in nepal on my own for at least a dozen trips and the only difficulty I have was occasionally ending up in someone's back garden...........
there is a danger of robbery but you can check that out locally, for instance I have heard that parts of Kullu can be dodgy That said
India has always seemed safer for me as a tourist than going shopping in London
The other idea is taking a porter/horseman to carry stuff - you put money into the local economy and you get an insight into the place more easily.
Just go

Maybe for first few solo treks, you should go to a place frequented by trekkers and/ or populated villages on the way or take a guide/ porter...and slowly as you develop confidence, you can go for higher passes/ peaks.

Even I'm going for my first solo trek next month...scared a-bit, but I've finalized the plan. I think Solo trekking is the truest form of trekking.

It helps if...
... at least one person is there with you...
... in case..., You know...

Go chopta Tunganath for solo Track its safe.

I had once trekked alone in Sandakphu in Darjeeling in January. Long long ago. I don't know what safety concerns you have. I had no issues. I never missed any one. People in the mountains are very friendly. And when you are alone you tend to make lots of friends which doesn't happen when you are with other friends.