GO: cannot find package 'ihelp/pkg/ihelp' in any of

Yesterday I was coding in GO and everything worked well. Today I get the following error message:

main.go:10:2: cannot find package "icalculate/pkg/idicalculateive" in any of:
    /usr/lib/go-1.10/src/icalculate/pkg/icalculate/algorithm(from $GOROOT)
    /home/ademxkartal/go/src/icalculate/pkg/icalculate/algorithm(from $GOPATH)

I have deleted the whole repository and did a git pull with a version from yesterday. Still I cannot compile the go-code. I have tried to compile a simple hello.go code and this works. So it seems that the GO Compiler is working in general.

Here is my go.mod file:

module icalculate

go 1.16

here is my module structure (working on Linux-Ubuntu):

/calculatorGo
|---- go.mod
|---- go.sum
   |/pkg
      |/icalculate
         |/algorithm
         |---- algorithm.go

This is what go env prints out:

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ademxkartal/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/ademxkartal/go"
GORACE=""
GOROOT="/usr/lib/go-1.10"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go-1.10/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build730659894=/tmp/go-build -gno-record-gcc-switches"