I just wanted to share a solution which I found while writing a post today. I wrote a post in MS-Word first and then pasted it in WP.However, the font size was corrupted and later I came to know it doesn't work with WP.What I tried then was copy the WP post, paste the same in Notepad (Plain Text editor) and re pasted the whole thing to WP. It works this time!!!
So, The logic behind this is that We need to use Plain text editor for copying and pasting into WP. RTF in Word format will not work. I know many would certainly know this logic but still wanted to post for those who doesn't know this yet just like me before 1/2 hour.