Hello Arun,
Thank you for the reply.
I appreciate your patience.
For Windows store issue, run system file checker(SFC) and see if it helps.
Refer:
Use the System File Checker tool to repair missing or corrupted system files
https://support.microsoft.com/en-us/kb/929833
System file checker is a utility in Windows that allows users to scan for corruptions in Windows system files and restore corrupted files.
Note: It may ask for Windows installation DVD to fix and to enable SFC to make more than minor repairs. Some files saved on your computer might get deleted when fixing corrupted files.
For sound issue, please refer this article.
Refer:
http://windows.microsoft.com/en-US/windows/no-sound-help#no-sound=windows-8&v1h=win8tab1&v2h=win7tab1&v3h=winvistatab1
Please keep us posted.
Thank you