I can't reinstall my device

What device are you talking about?

If your Mac predates Late 2011 model, according to its serial number:

https://discussions.apple.com/docs/DOC-6413

or meets it according to its specs:

http://www.everymac.com/systems/by_year/macs-released-in-2011.html

but is newer than March 15, 2010, you have to call AppleCare if any missing installer discs exist.

If it is older than March 15, 2010, e you can purchase the 10.6 retail, and upgrade to 10.6.6, and then use the Mac App Store to get 10.7, if it is not too old. The first MacBook Pros maximize their operating system at 10.6.8.

If it is late 2011 or newer, just contact the Mac App Store for the correct version of 10.7 to be made available to you when you restart the machine with command-R.

Note, newer Macs than July 25, 2012 10.8's release may not be able to install 10.7 at all either.

For more on which Macs are too old to install 10.7, see this tip:

https://discussions.apple.com/docs/DOC-2465