Did you download Ubuntu from the official site?
Are you actually trying to install Ubuntu or one of the many derivatives (Mint, Lubuntu, Kubuntu, etc.)?
Did you do an md5 checksum on the downloaded iso file?
The correct hashes are shown at the site below for the various Ubuntu derivatives.
https://help.ubuntu.com/community/UbuntuHashes
How to check it explained at the site below. If you only have windows installed, scroll down the page and that is explained.
https://help.ubuntu.com/community/HowToMD5SUM
Did you put Ubuntu on a DVD by burning it as an image? This is necessary as copying it is a waste of time.
Did you use some software to create a bootable flash drive? If so, what was it?
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