Corrections below:
1. An employee applying for leave as follows:
Since I have to go to my village along with my wife to sell my land, please sanction me one-weeks leave.
(Otherwise it implies you are selling your wife as well as your land)
2. An employee who's daughter was getting married and needed to apply for leave:
As my daughter is getting married, please grant a week's leave.
(Again, the original implies you are marrying your own daughter)
3. As my mother-in-law has expired and I am the only one responsible, please grant me 10 days leave.
4. Another employee applied for half days leave as follows:
Either
Since I have to go to the cremation ground at 10 o'clock and may not return, please grant me a half day casual leave.
or
Since I have to go tho the cremation ground at 10 o'clock and may not return, please grant me half a days casual leave.
5. I have a fever, please declare one days holiday.
6. A leave letter to the headmaster:
As I am studying in this school I am suffering from headache. I request you to give me leave today.
(This is correct only if this school is the cause of your headache)
7. I have a headache, please grant me leave for the day.
8. Covering note: enclosed herewith.
9. Another one:
Dear Sir: with reference to the above, please refer below.
This is incorrect!!! You would never normally say this, however if you had to you would write as above
10. My wife is suffering from sickness, may I be granted leave?
(Only husband at home implies she has more than one husband!!!!)
11. I am in well and hope you are also well.
You would never say 'in the same well.' This implies you have both fallen down a (the same) well.
12. A candidate's job application:
With reference to your advertisement for a ' Typist and an Accountant - Male or Female'... For the past several years I have performed both so am applying for the job.