The sound on my Acer aspire 5515 has an echo.

If that is the case, remove HDD and test. Replace if necessary.

You should use the P/N as printed on the batteries and also the voltage and current rating (higher current rating will give you longer run time)
http://www.amazon.com/Battery-5515-5187-5515-5831-5515-5879-BATBL50L6/dp/B004AXGPFM

http://www.buy.com/prod/new-laptop-battery-for-acer-aspire-5515-5187-aspire-5515-5705-5200mah/q/sellerid/25505856/loc/101/218061300.html

Please leave rating if it helps.

hi

you have problem with you OS just reinstall OS it will solve the problem

Click the start button (Or the windows icon - typically lower left on the task bar). Choose Restart. If you can't find that, choose Shutdown, once the laptop is off, press and hold the power button till you see the power come on.

It might be a keyboard shortcut you unintentionally pressed. On an Acer 5515 it

Sorry, your heading states Acer Aspire 5515 hence the confusion! At what point do you need a password? Is it a new or 2nd user laptop?

Does the laptop play CDs?
If so then when you start a DVD and before you play the movie, go into the audio setting and configure the speakers for laptop stereo speakers.
If you cannot hear music from the CD then check :-
1. The audio settings, volume not set to minimum and mute is not ticked (enabled)
2. Device manager - sound device is enabled and working, if not re-install the sound driver.

http://shop.ebay.com/i.html?_nkw=aspire+5500+keyboard&_sacat=0&_trksid=p3286.m270.l1313&_dmpt=PCA_Mice_Trackballs&_odkw=aspire+5515+keyboard&_osacat=0

I'm not 100% but the 5500 series all use the same board. What is the DFE model number on the back of the keyboard?

If you can't find a keyboard for it, you could always use a USB desktop keyboard until you find one.

Click this link it is basically the same. Let me know if you find a keyboard:

http://www.powerbrixx.com/reference/acer/3610_keyboard.htm