I left out three sentences, I hope you can see them.
1) Can you use his/her when writing a dissertion? Exmple:
The character stays fixed in a place whereas his/her consciousness moves freely in time.
2) There was no use in (is "in" necessary?) thinking of what might have been.
3) He carried the food on shore.
4) I recharge my cell phone every two day. I top it up twice a month. I'm a Vodafone subscriber.
5) I download music from the computer on my USB stick (how do you call it?)
1. It would be smoother if you didn't. It'd be better to make the pronoun and its antecedent plural, or (if you can't do that) use one or the other, whichever fits what you're writing about.
2. With or without "in" -- either is fine.
3. "onshore" (one word)
4. ... every two days.
5. There are several words for that device. I use "flash drive," but others say memory stick, USB stick, thumb drive, and I'm sure there are other terms for the same device.