: My HP PC recently crashed & I am trying to get all my info on a Gateway PC. I have discovered the Microsoft .NET frame 3.5.1 was uninstalled from this computer. I have tried to download 4.5.1 from the Microsoft site & it fails. I get an error code 643. Also, a support tech showed me that Microsoft in "service" has stopped. A support tech from AVG (antivirus) tried to fix my computer and she/he used TWEAKING.COM. Unfortunately she caused me to lose internet contact and then my computer crashed.