Why my mongodb Shell not getting started even after my mongodb server is running?
You have managed to kill your mongod middle of index build. 


  found 2 interrupted index build(s) on datastalk.stalk


Build of first index ({ v: 2, key: { _id: 1 }) didn't take long. Second index ({ v: 2, unique: true, key: { EMAIL: 1.0 }, name: "EMAIL_1", ns: "datastalk.stalk" }) is taking longer.. And at point of 35%, system got access violation when reading memory address 0x0000005648530000 

Do your machine have enough memory and memory DIMMs are good?

You can try to solve this problem with wiredTiger command line tools. Use dump to get your data from database to file, re-create your mongodb instance (remove all files from dbpath OR point your dbpath to other directory and restart mongod) and then import data back to database (re-creating needed indexes)