Logstash doesn't store in elasticsearch

I'm trying to do a script to load an apache file log.

The configuration files is correct because I started different time to load this file with the command logstash -f <path_conf_file> and I viewed the dot on the screen.

I interrupted different time by CTRL+C che process and killed it other time. Now at the restart of the server ELK with logstash too I don't see dot on the screen and the

http://localhost:9200/scenario1-*/_count

is alway to 0.

I check the log of elasticsearch (/var/log/elasticsearch/elasticsearch.log) and logstash (/var/log/logstash/logstash-plain.log) too but I don't found nothing.

I check the cluster too with http://localhost:9200/_cluster/health?pretty=true and I see empty sherd.

How could I solve this problem?

Thank you in advance
Franco

I may have found the problem, it could be due to the sincedb which contains the information of the file already processed. where do I find the synchedb configuration on logstash 6.2.1?

sincedb_path is configurable, but it's default depends on your Logstash settings for path.data; you can either find and delete it, or just specify a path where a new sincedb can be created.

My path.data is
path.data: /var/lib/logstash
In this folder I don't found sincedb,
I have this result
franco@serverElk:/var/lib/logstash/plugins/inputs/file$ ls -li/var/lib/logstash/plugins/inputs/file$ ls -li
total 0
what is the name? Where is stored?
My Os is debian server 9.0 and logstash 6.2.1.
Thank you
Franco