hOW do i clean the white strings hanging from my white blinds?

[hotHELL]

they have gone black and they are upsetting me...

Are they roman blinds? You can easily buy new string (John Lewis) & restring them.

If they're venetian blinds, I have no idea!

iw as wondering today i was htinkign bleach on a toothbrush

Venetian. Bleach on a toothbrush?