The suspend feature was working like a charm on my system
unless recently when it started to fail to resume from
suspended state. All i can see is a blank (dark) screen.
i tried following keys but got no visible response:
Ctrl+Alt+F1
Ctrl+Alt+F7
Ctrl+Alt+Del
Ctrl+Alt+BackSpace
NumLock
CapsLock

Surprisingly "Ctrl+Alt+PrtScr + REISUB" works and my system
reboots! this means that the system is running properly but
there is some issue with the Xserver/pm-suspend utility.

Note: i'm not a pro-bug-reporter so if i've missed some info OR
i've done some mistake please let me know :)

pm-utils hasn't changed for ages. So it's most likely a kernel issue.
Did you upgrade the kernel in the mean time?

What graphics hardware/driver do you use?
Could you attach your Xorg.0.log, dmesg and lspci.

Dear submitter,

as the package pm-utils has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1058701

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)