Use Free Windows Password Recovery/Reset Tool
Based on the description above, the best choice is to use a free Windows password recovery tool or Windows password reset tool. A Windows password recovery app helps you get back the forgotten Dell laptop password while the reset tool allows you to reset the lost password to blank or a new one.

Ophcrack
Ophcrack is one of the most popular Windows password crackers. More important, it's free of charge. Ophcrack cracks Windows passwords by using LM hashes through rainbow tables. It includes the ability to import the hashes from a variety of formats, including dumping directly from the SAM files of Windows.

How it works: Go to the official website and download the ISO image file. Next all you need to do is download and burn the Ophcrack Live CD and boot the computer you want to recover password for from the Live CD. After this, it will bring you to a desktop environment and start attempting to crack passwords. You'll see the passwords pop up in the top pane of the window, though, when it finds them. You can then reboot and log in to Windows using those passwords.

Offline NT Password & Registry Editor
Unlike Opchcrack, Offline NT Password & Registry Editor erases your Windows password instead of recovering it on Windows 7, Windows Vista, and Windows XP passwords (and some older Windows versions). Besides, it's also a registry editor.

How it works: To get started, visit the Offline NT Password & Registry Editor website and download the file described as the "Bootable CD image". Once downloaded, extract the ISO file from the ZIP file and burn the ISO image to a CD. And then boot from the CD by rebooting with the disc still in the drive. Offline NT Password & Registry Editor will start automatically. Next, just follow the instructions given on screen by Offline NT Password & Registry Editor. When the program finally deletes your password, remove the CD from the drive. Restart your computer and log in as you normally do. No password will be required.

Alternative: Windows Password Breaker
If the apps listed above don't work or you are not god at computer, it's better to try Windows Password Breaker when you forgot Windows password, which is an extremely easy yet efficient Windows password reset tool. You are able to safely reset your dell laptop password in no more than 5 minutes. No any computer skills required. However it is released as shareware.

How it works: 3 editions are available. Please choose the one that suits you best.
1. Download and install Windows Password Breaker in any computer.
2. Burn a bootable Windows password reset disk with CD/DVD or USB drive.
3. Boot the target computer from the burned disk.
4. Reset forgotten password by following the Windows Password Breaker instructions.