Grubby cot sheets

[sleepdeprived]

Not sure how DS's cot sheets got so horrible-looking - partly a colour-run maybe - but I cannot get them to look respectable! Label says don't bleach. I use Napisan to soak, and in the hottest wash possible - also Vanish. What to do?

(Very housewifey query, sorry)

Sorry but all I've had any luck with is...
...buying some more. John Lewis always have good elaticated ones at 'special purchase' in the sales.

Havent had any luck with biotex or glowhite in the past. What would happen if I bleached them?

Yes. Think I'll give it a go - nothing to lose but a squalid-looking sheet!