Could not start engine on Bluestacks

Possible solutions:

1.Change graphic's mode to DirectX. Please see: https://support.bluestacks.com/hc/en-us/articles/115003759823-How-can-I-change-the-graphics-mode-on-BlueStacks-3-
Make sure that you select DirectX, not OpenGL.

2.Make sure that Virtualization (VT-x) is enabled from BIOS. Refer to your manufacturer's site for assistance.

3.If you have the Avast Antivirus you need to uncheck the 'Enable hardware assisted virtualization' 
Please see https://support.bluestacks.com/hc/en-us/articles/115003212603-Solution-for-Avast-antivirus-makes-BlueStacks-run-slow-
Same applies for AVG, and perhaps a few other antivirus products.

4.Stop any other apps that are using the Virtualization feature(e.g. Daemon Tools, Hyper-V, VMWare)