No audio device is installed

You uninstalled the realtek drivers not the device, so no matter how many times you try to reinstall it via the device manager it will not work because your system needs driver software that will work with it. Uninstall the audio device via device manager, then reboot and install the appropriate realtek driver for your laptop from acers support/driver website. If you tell me the model in a comment I can give you the direct link.
http://www.acersupport.com/notebook/index.html


 I think its just a driver issue and that if you download the acer / aspire notebook realtek driver for your laptop your sound will start working 100%. If you think its an actual hardware issue than the only way to resolve it is by contacting acer directly. 

http://www.new-drivers.com/files/sound/Realtek?gs.realtekgeneral&gclid=CN37x6mp1ZoCFRUhnAod3Fz22g

need to download your audio card driver