Its gone by Design, Until Windows 10 build 2004 we had an options in registry to bring it back. But Microsoft took is away as well. [NAME]  Correction, Microsoft is the one pushing it, Dell and other OEMs are following it. Microsoft Believes there S0 (modern standby mode) is the future. FAQ Modern StandbyAll newer Dell laptops now use the Microsoft mandated Modern Standby. The old legacy Standby S3 is no longer supported. All newer Dell Laptops support Modern Standby S0 sleep only. The BIOS is written with this mandate in mind.
When I open command prompt and type 'powercfg /a', S3 sleep is disabled because S0 sleep is on. I have found a way to turn off S0 sleep but S3 sleep still stays disabled due to the firmware not supporting it.  I've tried searching through the BIOS but I haven't found much related to sleeping. I've also searched all over the internet but either nothing works or I can't find anything about this issue. How can I fix this? If there is something in the BIOS that I missed, please tell me. As far as I know, my BIOS is up-to-date.  All help is appreciated.        
Inspiron 5502, S3 sleep unsupported