Which Windows version are you using ?
If it's XP, Dell computers usually came with a CD labelled Dell XP Re-installation CD or similar when they were new - that can be used the same way as a regular Windows XP CD, but only on the same model it came with. They often also came with a Dell Drivers and Applications disk, or similar.
If it's XP...
You also have a second copy of iexplore.exe already on the computer that is exactly the same as the one that was in C:\Program Files\Internet Explorer - the malware (most malware these days is NOT a virus) may have corrupted the one that's there.
Control Panel - Classic view - Folder Options - View tab.
Enable Show Hidden files and folders (click on the circle so it shows a dot)
Disable Hide extensions for known file types (click on the checkmark to remove it)
You may also need to
Disable Hide protected operating system files (click on the checkmark to remove it)
Click on OK at the bottom of the Folder Options window.
Go to C:\Windows\System32\dllcache
Search for: iexplore
RIGHT click on iexplore.exe , select Copy.
Go to C:\Program Files\Internet Explorer
RIGHT click on the folder Internet Explorer, select Paste.
Reboot and try IE.