How to make it seem like a lot of time has gone by
Question: My character fell into a coma. How do I make it seem in the next 5 chapters that a lot of time has gone by? Answer:
I would suggest you brainstorm a list of things your character would notice that would clue him/her into the fact that time has gone by.
These can be straightforward -- such as having a doctor say how long the coma lasted, the date on a computer screen, or a glance out the window to see that summer has turned into winter.
If you're trying to create a mystery in which the main character is being deliberately misled about how long the coma lasted, you might give him more subtle clues, such as changes in the relationships between certain characters, the healing of a broken bone, a growth spurt in a child or a plant, etc.
It really depends on what kind of story you are telling and the environment the character finds himself in. Some environments will offer more obvious clues than others.