spare nut?blender model no 12089?

It's a Cordon Bleu Blender Liquidiser - you do not help your case by keeping the brand name a secret...

Second hand models are advertised for £10. Buy one and steal the nut from it.

The thread form is very probably metric - nip down to a decent hardware store in your area and buy a few nuts that look as if they might fit - perhaps 10p each.

Ask an old codger who lives nearby and has a small workshop - old codgers just love to help people in difficulty.

Old Codger...
March 2017