In cheat engine if unknown initial value is not there what to do?

What you need to do is start a new scan.

Just click on the "new scan" button, then click on the scan type and you will find "unknown initial value" and your done.

Alternatively, if you searched for "unkown initial value", the list will often appear blank. This is because there are too many results for the program to display simultaneously. You will need to narrow your serach by selecting another option (for example: 'Increased Value' if the value your looking for is increasing, or "Unchanged Value" if the value should be the same as it was in the last search) and click Next Scan to remove any of the results from the previous scan that don't match. Try to search often, making full use of options like "Unchanged Value" and "Value Between" to remove the rather large number of values than may happen to change similar directions to your searches, but are not relevant to what you want (these usually rapidly shift values, but rarely do so in small incriments, so repeated value range searches remove them easily).