If the Covid-19 investigation shows China to have been negligent,should the U.N demand some degree of reparation for the damage to economies?

There are five U.N countries that can veto any resolution. China is one of them.

IF - big if.   The UN can demand whatever they feel like but do you really believe China is going to do anything?   And as for sanctions, that only hurts the people (who I suppose could rise up again their leaders but I doubt that would ever happen).

Personally I refuse to buy anything from China, and have done for a long time, well before the virus because it took forever to be delivered and was all too often shoddy, if cheap. 

China is a lot different to Saddam/Iraq!!

Should have thought about this before allowing China to control the energy and communications infrastructure of other countries that could easily be damaged by any retaliation.

America isnt signed up to international law neither is China a much bigger nation it is the new boss get used to it 

Do you think China gives two fùcks about what the UN demands?

They can demand it but they're never going to get it

Yes, but good luck getting it.