Fan doesn't work after start up

[Tyler noble]

(Before you read this i just want to say my pc knowledge is very little and im really dumb)

 My fan will work slowly for a few seconds whenever i turn the pc on but will come to a stop and no longer work i have taken off the side panel to make sure nothing was in its way (the pc is very dusty but the fan in question isnt dusty enough for that to be a problem) ive looked on other techsupport forums for stuff like this and have found some stuff that just hasn't worked with my pc

(Just some stuff about the pc it was made around 3 and 1/2 years ago and hasnt had any changes the fan just now started doing this)

[TylerDurden!]

36 minutes ago, Tyler noble said:

My fan will work slowly for a few seconds whenever i turn the pc on but will come to a stop and no longer work

get a replacement fan for whatever fan is failing. 

[LogicalDrm]

Please list the relevant specs. This need motherboard model and fan model. Also where/how fans are connected.