Before you make up your mind just to read the steps, I would like to warn you that reading the full post will only takes some minutes and will assure you of no loss of data/software. Ignoring the full post will risk you to dangers of data/software loss permanently.
I am tech loving person, i keep experimenting with technology. I use and Android 4.0.4 (Ice Cream Sandwich) on my Spice Mi-495. Spice is an Indian manufacturer of mobiles. I was trying to install android device manager on my phone. It got installed but when i opened it, it said " Google Play Services, which some of your applications rely on, is not supported by your device. Please contact your manufacturer." Whoosh! The device manager closed.
I then researched about Google play services and found that it is an internal app which Google and many other app developers of android use to run app on android. This was not installed on my phone. I tried to install it through play store and even manually. It showed an error "This app is incompatible with other apps using the same shared user id(s)." I wasn't able to get that, i researched, and i found that this type of error happens when the manufacturer of phones have not done a clean job. And this was also the reason why I Google apps don't get updated.
This was something which only the manufacturer can fix, but i knew they are not going to replace or repair this. And i am not the one to keep mum. I researched for months and months over the internet. I found and tried many solutions but none of them worked. Lastly, On a very helpful site called xda-developers, I found a working solution. I tried it....Whoooo, it worked, Google Play services got installed. I tried updating Google apps and yes, they got updated.
I was extremely happy and thought to help all those who are still stuck either with the error saying Google Play Services cannot be installed or the error saying incompatible shared user id(s). This solution will work for both the errors.
Here is what you should do:-