Here are the corrections with rules:
1. I like fruits after meal.
Correct: I like fruit after a meal.
Error: Fruit is uncountable when meaning food in general.
2. Either of the men were supposed to be present.
Correct: Either of the men was supposed to be present.
Error: Either is singular.
3. One of the players are missing.
Correct: One of the players is missing.
Error: The subject is One, not players.
4. The audiences are requested to be silent.
Correct: The audience is requested to be silent.
Error: Audience is a collective noun - singular.
5. It is a good weather.
Correct: It is good weather. / The weather is good.
Error: Weather is uncountable, no a.
6. I love the poetries of Sarojini Naidu.
Correct: I love the poetry / poems of Sarojini Naidu.
Error: Poetry is uncountable.
7. He wears a spectacles.
Correct: He wears spectacles / a pair of spectacles.
Error: Spectacles is always plural.
8. This trousers is loose.
Correct: These trousers are loose. / This pair of trousers is loose.
Error: Trousers is always plural.
9. Politics are a dirty game.
Correct: Politics is a dirty game.
Error: Politics looks plural but is singular as a subject.
10. He killed some deers.
Correct: He killed some deer.
Error: Deer has same form in singular and plural.
11. Sheeps are very useful.
Correct: Sheep are very useful.
Error: Sheep has same form.
12. I do not like vegetable.
Correct: I do not like vegetables.
Error: For general dislike, use plural countable.
13. He has many grey hairs.
Correct: He has grey hair.
Error: Hair is uncountable. Grey hairs is only for counting individual strands.
14. The news have been conveyed to him.
Correct: The news has been conveyed to him.
Error: News is singular.
15. The sceneries of Kashmir are charming.
Correct: The scenery of Kashmir is charming.
Error: Scenery is uncountable.
16. Neither of the sisters are intelligent.
Correct: Neither of the sisters is intelligent.
Error: Neither is singular.
17. I have packed my luggages.
Correct: I have packed my luggage.
Error: Luggage is uncountable.
18. He runs a shop of furnitures.
Correct: He runs a furniture shop / shop of furniture.
Error: Furniture is uncountable.
19. I have seen a flock of sheeps.
Correct: I have seen a flock of sheep.
20. Gurmeet bought two dozens eggs.
Correct: Gurmeet bought two dozen eggs.
Error: After a number, dozen remains singular.
