After uninstalling Ubuntu my one drive, on which Ubuntu was installed is missing just now as I’m using Windows 7. Please help me.
You can use Windows login Recovery and there is no need to install the system anymore.
Another thing to try is go to any directory click the arrow on the organize tab,select"Folder and Search Options", click "view" tab, clear the check mark from "Hide empty drives in the Computer folder"
Even after removing Ubuntu the drive is either using the file system Ubuntu was installed on (probably ext3 or ext4) or it is unformatted.
Go to "Start > All programs > Administrative Tools > Computer Management".
Within the Computer Management select "Storage > Disk Management".
You will get a list of all available drives and partitions. Locate your old Ubuntu Disk/Partition, right-click it and select format (this will delete all content of the drive so make really sure you selected the correct one.
As a side note/warning:
In Windows 7 you will also see a 100MB or 200MB Partition named "System-Reserved". You really don't want to touch this one ~ it contains necessary boot files, the Windows Recovery and BitLocker.