First and foremost try and find out the reason/reasons your team feels demotivated. Once you know the reason its easier to focus and divert your energy towards a specific direction. As for motivational ppt's are concerned, you can get them at a click of the mouse - but you need to have some relevant stuff. I can help you too provided you are more specific.
Linkedin ; Amit CM
PPT will not serve your purpose as stated by Amit. For every individual need for motivation are different. If the whole team is down there could be something wrong with strategy, product, Policy, market, customer perception, promotion, price and many more. Motivation has to come from within to make things happen. You can take a horse to river to drink water, Do you think it will drink water?How can you make it thirsty to drink !!!
There are many video clippings on motivation on you tube to charge them will be a better option.
Hope you are motivated to help your team members.