I recently removed Ubuntu 10.04 from my laptop for a few reasons (limited battery life, must-have apps not existing, such as Windows Live Writer that I’m using to write this post, and generally no reason to use it instead of Windows 7). In any case, my first step was to kill the Linux partition in windows from the Disk Management console, however upon restarting, Grub (a common Linux boot loader) didn’t appreciate that I had messed around with my bootable partitions, and refused to allow me to get into Windows. After a little hunting around, the solution is pretty simple (assuming you have a Windows 7 bootable DVD nearby):
1) Boot from the DVD, select your language, and get to the second screen, where you’re going to select “repair computer” (or repair my/your computer – I can’t exactly remember the wording).
2) Navigate to the command prompt and use the following commands in sequence (pressing the enter key after each command).
a) bootrec /fixmbr
b) bootrec /FixBoot
3) Reboot your machine
This information is paraphrased – I found the solution at the Neowin forums, originally posted by +Snowl. Useful information to be sure, if you randomly install linux every few months.
Syd
Header image courtesy of Craig1black – Boot Error / CC BY 2.0

You got rid of Linux already? How sad. I thought you had fixed the battery drain issue?
Yeah – it’s sadly part of my habitual cycle, where I use it for about a month, enjoy the progress it has made, then come to the realization that it still doesn’t provide much incentive for me to use, over Windows 7. I love the philosophy behind it, which is why I keep come back to it – but for day-to-day, Windows 7 is presently hard to beat.
I was able to substantially improve battery life under Linux, that’s true (at least based on the meter app that comes included with Ubuntu), but in actual use, power usage is still not as efficient as our Redmond based friend. I’ll probably give subsequent Ubuntu revisions a try, though likely under a virtual machine.