My party has run through LMoP and is now in CoS when they returned and the world to be in the middle of a industrial revolution any help on what to do whith it?

Change the setting to eberron?

That won't work because the players have gotten very attached to the town and area.

Also the players have backstorys and goals that wouldn't make sense in eberron

Then, maybe just steal stuff from eberron. Put in that magical railroad, make artificers common and make Druids sad, angry and insular, throw in airships, gas lamps and pollution. Just go steampunk. 
You could probably also steal stuff from ravinca.

Make most of the NPCs Artificers, just change the scenery around a bit, tear up all the farms, more pollution, huge factories, and more trains and firearms. Do that and you should be good.

It would seem to me that the main question would be how much time has passed. An "industrial revolution" typically takes decades to show a lot of changes. Historically, the industrial revolution seems to have spanned from 1760-1830/40 kind of time frame. Magic might speed that up but on the other hand magic is also likely to mitigate against an industrial revolution since cantrips are available to perform a lot of menial tasks. Depending on how easily accessible it is to learn a cantrip or two like prestidigitation, mage hand, mold earth, shape water - there is quite a bit that can be accomplished without enhanced technology.

You'll also need to decide what an industrial revolution in a magical society would look like. Would the "industrial" improvements be based on magic or on science? Magic could potentially do anything depending on how you want to run it. Magic would appear to be a source of energy which when harnessed might replace steam energy without all the pollution that resulted from burning coal. Would running magic power plants deplete magic from the weave and create anti-magic zones? Is magic just unsuited to powering "industrial" scale innovations?

There are lots of details that would affect how an "industrial" revolution might work in your game world that you might want to consider.

It’s also worth thinking about the social upheaval that an Industrial Revolution causes. The historical Industrial Revolution was associated with a shift of population away from the countryside into the rapidly growing cities (especially in the north of England). So, that village or small town that your PCs knew might now be much quieter, with many of the younger inhabitants having moved away. Traditional cottage industries may be collapsing due to competition from factories. There may be influxes of labour from marginalised communities: perhaps factory owners are recruiting cheap-to-exploit goblins or kobolds? 

What resources are being exploited to drive the industrialisation? Does their extraction bring conflict? Timber from forests under elven or druidic aegis? Minerals in territories controlled by dwarves, orcs or monsters? Are they cooperating, tolerating or resisting the extraction? Is involuntary labour being used? If the industry is based on magic, those resources could include some rare and exotic materials, such as monster parts. 

I suggest whole-heartedly taking the premise of the games Assassins Creed: Syndicate and Thief, maybe have the order of (insert name) recruit the party to overthrow the tyrannical but shadowy cabal that operate behind the scenes and manipulate the world. Both sides are trying to locate some secret cache of magic underground, one side promoting freedom (chaos) and the other rigid systems of life (law).

The First Industrial Revolutiuon was not a quick process. It lasted for 60-80 years (that is, two or more generations).

So don't have the one in your game go too fast. Don't jump straight to trains and assembly lines and steam and electricity.