Rescue truncated data from incorrect column type I have mistakenly inserted a variable 18-20 digit variable into an unsigned INT() column. 

The data has been truncated to the max 32bit length so all my data is displayed as "4294967295" 

Is there any way to retrieve the original data?
The basic answer is: No.

Do you have a record of the 18-20 digit value somewhere?  In another location in your database, on a piece of paper on you desk, etc?  If so then use the source information to correct your error.

You have not indicated which database software you are using, which can make a difference for many issues.