I think you have made a mistake, kak111 as when MC pulls in it's contact above it is made and there is nothing to switch MC off.
For case 1, you need two level switched, one to switch the pump on at the "low" level, and another to switch it off at the tank "high level".
case 2 :
"the pump should get off when the water level reaches to its maximum marked level * and after that some man start the pump manually (and then after filling the tank to the required level~ the pump should stop again automatically)"
This does not make sense.
* = tank filled up OK same as case 1
~ = then what - tank over flows? or is ~ the maximum level and * some intermediate (chosen) level.
Frank