How do i install windows 7 64 bit over 32 bit windows 7

[akash0007]

hello everyone
i bought new pc and every thing was fine but when i noticed that my pc was using only 3.49 gb out of 8 gb installed . i am having windows 7 32 bi so i wanted to install windows 7 64 bit.
so,when i wanted to install ,there was an error while expanding the windows file
i was helpless.so i reached here.
i have-intel motherboard-dh61ww,ram of 8 gb 4x2 ,core i5 processor -2320
i got error that windows cant install because file was missing or currupt.
what i have tried
i tried installing takingout one slot with 4 gb ram but failed
i bought new dvd of windows 7 but failed
updated bios but failed
i checked with upgrade adviser every thing was fine my computer is capable of 64 bit but i am not able to install it
i want to use 8 gb ram so i wanted to install windows 7 64 bit
PLS HELP

 

[zigzag3143]

When changing from 32 bit to 64 bit you have to do a clean install. Sorry

 

[akash0007]

Yes i was doing clean installation

 

[akash0007]

while expanding windows file it gave error.

 

[akash0007]