I ran a software update (Ubuntu 14.04) on my laptop over the weekend, which included an update from kernel 3.13.0-24 to 3.13.0-27, among other things. Today i had to take my laptop to work, so closed the lid and put it in my bag. However, it never went into suspend mode! I tried several times, even rebooting. Finally I tried the previous kernel from the grub menu (reverting back to the -24 one) and suspend works the same as it always had before.

Did something suspend related change between the -24 and -27 kernels used in Ubuntu 14.04? I think by only reverting to a previous kernel to temporarily fix it, i've ruled out any other software changes made during the weekend's upgrade.