Logical partitions deleted automatically

[SANDEEP1282]

I was trying to custom install windows 7 on a windows 8.1 pc due to virus infection. When i deleted the c drive (system disk), two more partitions got deleted thereby causing loss of data. How did this happen?. However, One partition is still intact. Please explain.

 

[jsmithepa]

Logical partition types are attached to their masters. You delete master, logical goes with it, but am surprised it didn't give you a warning, maybe you were clicking like a madman.