If your computer will not come out of sleep mode this can be caused by settings, incompatibility and hardware/software problems.
Settings
Firstly make sure that there are no settings causing the issue, by this I mean the power saving settings for any hardware should be disabled, if power saving is invoked and the computer is put to sleep then it can have issues powering back on.
As here the computer is able to turn off the network card, if it’s unable to power it back on which can be common when resuming from sleep or standby it can cause the computer to hang.
Ensure that any unneeded hardware is disabled via device manager, this can be modems, PCMCIA/Card bus slots; Unneeded hardware not only puts and unnecessary load on your computer, but can also be the root of an issues such as when a computer will not come out of sleep mode .
Updates
Not all computer hardware is compatible with sleep mode, make sure you are using the very latest drivers for any hardware, this includes upgrading your computers firmware if the computer is a number of years old. (be careful though double and triple check you have the correct firmware, as installing the wrong one can destroy your computer)
Hardware Problems
The first place to look for hardware problems with sleep mode is the computer’s memory or RAM as this stores all the data when in sleep mode; This needs to be checked for problems, most computer have hardware checking via the POST or power on self test, this can be invoked via the computers BIOS.
Other computers such as Dells have further hardware diagnostics that can be run by hitting the F12 key on startup and selecting diagnostics.
If you have a pc that has no hardware checking use an application such as SiSoftware-Sandra the free lite version should suffice and will enable you to check most computer hardware.
Computer Wont Come out of Hibernation Mode
Hibernation mode, although being pretty similar to sleep mode works in a different way as its stores the contents of the RAM in a file on the hard drive, if the hard drive has any issues the image cannot be read and attempting to come out of hibernation will fail, then the computer can only start from scratch causing you to lose any changes made in the hibernation file.
If you have any such issues make sure you run CHKDSK over the hard drive and then defragment it as well.
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