I second recommendation for Terry Pratchett- he is funny, cheering. Also Jasper Fforde, but he is more literate and takes more effort.
I also recommend (w lst in series):
Christopher Moore - Practical Demonkeeping
Steven Brust- The Phoenix Guards or any Vlad Taltos book
Neil Gaiman- e.g. Stardust
Charles De Lint- most of his books are fairly light
Liz Williams- The Snake Agent
Connie Willis- any of the time travel books besides The Doomsday Book (which is fab but not lighthearted)