Windows 7 Stuck at a black screen with blinking cursor [have a dual boot with ubuntu]

Hi and welcome to the forum

Q#1 Answer: Possibly. Can you tell us whether or not you installed your Ubuntu before or after your Win7 on that laptop? There are software repairs that are available for laptops as well as desktop PCs; but laptops have some special requirements you have to look at, and once done you can proceed with software repairs, and then hardware testing. It's also customary when asking for help on a crashed computer to provide us with the exact Make/Model of the laptop or computer. For example, a Dell Inspiron 15-3000 series.

Q#2 Answer: Let's start with this laptop troubleshooting guide I wrote a couple of years ago: So many problems - Tech Support Forum. Take a look at my POST #5, under BIGBEARJEDI (me). As mentioned in my post, this is a catch-all troubleshooting guide and the "how-to" on fixing your own laptop. I strongly suggest you print this document out on another computer such as a friend's, library computer, or family member's computer as it is several pages in length and you don't have a working computer (except for the one you used to post your help request)--unless you did from a phone or tablet as many users here do when facing a primary computer crash.
We see hundreds of laptop crashes every year, and this document is how most of us Techs go about fixing them.

Post back your laptop specs as requested, and proceed with troubleshooting your laptop. It's a lengthy process and if you've never worked on a dead or crashed laptop before expect it to take several days or even a couple of weeks to get to the bottom of your problem. If you're not too technical or don't have that kind of time, you can take it to a licensed computer Tech at your local repair shop and expect to pay $65-$130 US for a diagnosis--not the actual repair. Laptop repairs can run from $140-$1500 US.

Don't forget to check your Alerts in the notifications portion of your MY ACCOUNT here on WF, so that you can receive Alerts on your mobile device or other computer when one of us answers you if you have further questions. And, we are volunteers here and have lives, so we don't always answer right away so be patient and check your E-mail often. We are here 24x7x365, so if you post a question in the middle of the night our time (USA), we might not get to it right away, but one of our forum volunteers in Europe or Asia may get to answer it. Usually, we attempt to answer all questions asked with 24 hours of you posting it. And we do a pretty good job!

Best of luck,
<<<BIGBEARJEDI>>>