Ela,
I am guessing you are trying to use the WPF Framework. 
For some unknown reason the OpenUIPlayersDB.linq script is not included in the WPF framework distribution as one would expect.
The good news is that you can simply grab the file from the Android Framework distribution. the file is located in the Sample folder of the zip (C:\SAP\MobileSDK3\AgentryToolkit\OpenUISDK\Android\SMPAgentryClientFramework-Android-70.10.0.zip). The file is also in the iOS Framework under the iOS\SampleApp folder but is named OpenUIPlayersDB.txt instead of .linq
The file is just a text file SQL script that you can bring into your favorite SQL editor. The file was written for SQL Server I believe but can be run against any DB with some minor tweaks as needed based on how the DB handles it.
--Bill